Allow any system to become UAVCAN controlled by setting UAVCAN_ENABLE to 3.

ROMFS/px4fmu_common/init.d/rcS

@@ -391,6 +391,14 @@ then
 	#
 	set TTYS1_BUSY no
 
+	#
+	# Check if UAVCAN is enabled, default to it for ESCs
+	#
+	if param greater UAVCAN_ENABLE 2
+	then
+		set OUTPUT_MODE uavcan_esc
+	fi
+
 	# If OUTPUT_MODE == none then something is wrong with setup and we shouldn't try to enable output
 	if [ $OUTPUT_MODE != none ]
 	then

src/modules/uavcan/uavcan_params.c

@@ -45,9 +45,10 @@
  *  0 - UAVCAN disabled.
  *  1 - Enabled support for UAVCAN actuators and sensors.
  *  2 - Enabled support for dynamic node ID allocation and firmware update.
+ *  3 - Sets the motor control outputs to UAVCAN and enables support for dynamic node ID allocation and firmware update.
  *
  * @min 0
- * @max 2
+ * @max 3
  * @group UAVCAN
  */
 PARAM_DEFINE_INT32(UAVCAN_ENABLE, 0);