FMUv1: Fix CAN compilation

cmake/configs/nuttx_px4fmu-v1_default.cmake

@@ -98,6 +98,7 @@ set(config_module_list
 	modules/controllib
 	modules/uORB
 	modules/dataman
+	modules/uavcan
 
 	#
 	# Libraries

src/modules/uavcan/uavcan_main.cpp

@@ -530,8 +530,10 @@ int UavcanNode::start(uavcan::NodeID node_id, uint32_t bitrate)
 	 * If no transceiver is connected, the RX pin will float, occasionally causing CAN controller to
 	 * fail during initialization.
 	 */
+	#ifdef GPIO_CAN1_RX
 	stm32_configgpio(GPIO_CAN1_RX);
 	stm32_configgpio(GPIO_CAN1_TX);
+	#endif
 	stm32_configgpio(GPIO_CAN2_RX | GPIO_PULLUP);
 	stm32_configgpio(GPIO_CAN2_TX);