Fixed coverity warnings for targets folder. Also fixed one bug while copying sim.

Author: Teppo Järvelin

features/cellular/easy_cellular/CellularConnectionFSM.cpp

@@ -136,7 +136,7 @@ bool CellularConnectionFSM::power_on()
 void CellularConnectionFSM::set_sim_pin(const char * sim_pin)
 {
     strncpy(_sim_pin, sim_pin, sizeof(_sim_pin));
-    _sim_pin[sizeof(_sim_pin)] = '\0';
+    _sim_pin[sizeof(_sim_pin)-1] = '\0';
 }
 
 bool CellularConnectionFSM::open_sim()

features/cellular/framework/AT/AT_CellularNetwork.cpp

@@ -310,6 +310,7 @@ nsapi_error_t AT_CellularNetwork::connect()
 
 nsapi_error_t AT_CellularNetwork::open_data_channel()
 {
+#if NSAPI_PPP_AVAILABLE
     tr_info("Open data channel in PPP mode");
     _at.cmd_start("AT+CGDATA=\"PPP\",");
     _at.write_int(_cid);
@@ -323,6 +324,9 @@ nsapi_error_t AT_CellularNetwork::open_data_channel()
      * If blocking: mbed_ppp_init() is a blocking call, it will block until
                   connected, or timeout after 30 seconds*/
     return nsapi_ppp_connect(_at.get_file_handle(), callback(this, &AT_CellularNetwork::ppp_status_cb), NULL, NULL, _ip_stack_type);
+#else
+    return NSAPI_ERROR_OK;
+#endif // #if NSAPI_PPP_AVAILABLE
 }
 
 /**

features/cellular/framework/targets/QUECTEL/BG96/QUECTEL_BG96_CellularStack.cpp

@@ -99,7 +99,7 @@ void QUECTEL_BG96_CellularStack::handle_open_socket_response(int &modem_connect_
 }
 nsapi_error_t QUECTEL_BG96_CellularStack::create_socket_impl(CellularSocket *socket)
 {
-    int modem_connect_id;
+    int modem_connect_id = -1;
     int request_connect_id = socket->id;
     int remote_port = 0;
     int err = -1;
@@ -246,7 +246,9 @@ nsapi_size_or_error_t QUECTEL_BG96_CellularStack::socket_recvfrom_impl(CellularS
     recv_len = _at.read_int();
     _at.read_string(ip_address, sizeof(ip_address));
     port = _at.read_int();
-    _at.read_bytes((uint8_t*)buffer, recv_len);
+    if (recv_len > 0) {
+        _at.read_bytes((uint8_t*)buffer, recv_len);
+    }
     _at.resp_stop();
 
     if (!recv_len || (_at.get_last_error() != NSAPI_ERROR_OK)) {