Use the underlying memory pointer to determine where memory resides in ToDlPack (#1093)

* Use the underlying memory pointer to determine where memory resides

For tensor slices, ToDlPack was previously incorrectly assigning the device_type
because Data() pointed to the offset. When using MATX_MANAGED_MEMORY, cuPointerGetAttributes
cannot tell the difference between CPU and GPU memory

* Fixup - add const method to GetStorage()

* Revert "Fixup - add const method to GetStorage()"

This reverts commit c4314f6.

* Add const to GetStorage call

Author: dylan-eustice

include/matx/core/tensor.h

@@ -1470,8 +1470,9 @@ MATX_LOOP_UNROLL
     t->device.device_id = 0;
 
     // Determine where this memory resides
-    auto kind     = GetPointerKind(this->Data());
-    [[maybe_unused]] auto mem_res  = cuPointerGetAttributes(sizeof(attr)/sizeof(attr[0]), attr, data, reinterpret_cast<CUdeviceptr>(this->Data()));
+    void *data_ptr = const_cast<tensor_t*>(this)->GetStorage().data();
+    auto kind = GetPointerKind(data_ptr);
+    [[maybe_unused]] auto mem_res = cuPointerGetAttributes(sizeof(attr)/sizeof(attr[0]), attr, data, reinterpret_cast<CUdeviceptr>(data_ptr));
     MATX_ASSERT_STR_EXP(mem_res, CUDA_SUCCESS, matxCudaError, "Error returned from cuPointerGetAttributes");
     if (kind == MATX_INVALID_MEMORY) {
       if (mem_type == CU_MEMORYTYPE_DEVICE) {