Camera: fix possible nullptr on setCallbacks

Fix crashes like this:
05-03 20:55:09.029  6254  6254 F DEBUG   :       #00 pc 00000000  <unknown>
05-03 20:55:09.029  6254  6254 F DEBUG   :       DotOS#1 pc 000ec8ab  /system/lib/libcameraservice.so (android::CameraHardwareInterface::notifyCallback(android::hardware::camera::device::V1_0::NotifyCallbackMsg, int, int)+18) (BuildId: 078b8118f1d0503988dc8f86045848d8)
05-03 20:55:09.030  6254  6254 F DEBUG   :       DotOS#2 pc 0002e6cd  /system/lib/android.hardware.camera.device@1.0.so (android::hardware::camera::device::V1_0::BsCameraDeviceCallback::notifyCallback(android::hardware::camera::device::V1_0::NotifyCallbackMsg, int, int)+96) (BuildId: a964b5ab287096bfb4e9fb1357483757)
05-03 20:55:09.030  6254  6254 F DEBUG   :       DotOS#3 pc 00013783  /system/vendor/lib/camera.device@1.0-impl-htc_msm8960.so (android::hardware::camera::device::V1_0::implementation::CameraDevice::sNotifyCb(int, int, int, void*)+46) (BuildId: 183c013753a49cdceaf880f00b6083b7)
05-03 20:55:09.030  6254  6254 F DEBUG   :       DotOS#4 pc 00038b99  /system/vendor/lib/hw/camera.vendor.msm8960.so (android::QCameraStream_preview::processPreviewFrameWithDisplay(mm_camera_ch_data_buf_t*)+128)
05-03 20:55:09.030  6254  6254 F DEBUG   :       DotOS#5 pc 000086ff  /system/lib/libmmcamera_interface2.so
05-03 20:55:09.030  6254  6254 F DEBUG   :       DotOS#6 pc 00008855  /system/lib/libmmcamera_interface2.so (mm_camera_msm_data_notify+248)
05-03 20:55:09.030  6254  6254 F DEBUG   :       DotOS#7 pc 0000736f  /system/lib/libmmcamera_interface2.so
05-03 20:55:09.030  6254  6254 F DEBUG   :       #08 pc 000a6b67  /apex/com.android.runtime/lib/bionic/libc.so (__pthread_start(void*)+20) (BuildId: 1c34385a63ae9f807822c87c6b4126d2)
05-03 20:55:09.030  6254  6254 F DEBUG   :       #09 pc 00060101  /apex/com.android.runtime/lib/bionic/libc.so (__start_thread+30) (BuildId: 1c34385a63ae9f807822c87c6b4126d2)

In case of HTC One M7, the nullptr appears because of this call:
https://github.com/AICP/frameworks_av/blob/q10.0/services/camera/libcameraservice/CameraFlashlight.cpp#L528

And while we're on it, lets fix some more possible nullptr's too.

Change-Id: I2f67756d576d62560a2e65af55ab868bfc3e36ba
Signed-off-by: Julian Veit <claymore1298@gmail.com>

Author: chaosmaster

services/camera/libcameraservice/device1/CameraHardwareInterface.cpp

@@ -228,7 +228,9 @@ hardware::Return<void> CameraHardwareInterface::handleCallbackTimestampBatch(
             msgs.push_back({hidl_msg.timestamp, mem->mBuffers[hidl_msg.bufferIndex]});
         }
     }
-    mDataCbTimestampBatch((int32_t) msgType, msgs, mCbUser);
+    if (mDataCbTimestampBatch != nullptr) {
+        mDataCbTimestampBatch((int32_t) msgType, msgs, mCbUser);
+    }
     return hardware::Void();
 }
 
@@ -777,7 +779,9 @@ void CameraHardwareInterface::sNotifyCb(int32_t msg_type, int32_t ext1,
     ALOGV("%s", __FUNCTION__);
     CameraHardwareInterface *object =
             static_cast<CameraHardwareInterface *>(user);
-    object->mNotifyCb(msg_type, ext1, ext2, object->mCbUser);
+    if (object->mNotifyCb != nullptr) {
+        object->mNotifyCb(msg_type, ext1, ext2, object->mCbUser);
+    }
 }
 
 void CameraHardwareInterface::sDataCb(int32_t msg_type,
@@ -794,7 +798,9 @@ void CameraHardwareInterface::sDataCb(int32_t msg_type,
              index, mem->mNumBufs);
         return;
     }
-    object->mDataCb(msg_type, mem->mBuffers[index], metadata, object->mCbUser);
+    if (object->mDataCb != nullptr){
+        object->mDataCb(msg_type, mem->mBuffers[index], metadata, object->mCbUser);
+    }
 }
 
 void CameraHardwareInterface::sDataCbTimestamp(nsecs_t timestamp, int32_t msg_type,
@@ -813,7 +819,9 @@ void CameraHardwareInterface::sDataCbTimestamp(nsecs_t timestamp, int32_t msg_ty
              index, mem->mNumBufs);
         return;
     }
-    object->mDataCbTimestamp(timestamp, msg_type, mem->mBuffers[index], object->mCbUser);
+    if (object->mDataCbTimestamp != nullptr) {
+        object->mDataCbTimestamp(timestamp, msg_type, mem->mBuffers[index], object->mCbUser);
+    }
 }
 
 camera_memory_t* CameraHardwareInterface::sGetMemory(