ROMFS: fix SYS_USE_IO==0

When SYS_USE_IO was disabled, px4io would not start and thus there was no
RC. SYS_USE_IO=0 is interesting on Quads to avoid the IO and reduce output
latency.

Tested on Pixhawk 1 and Pixhawk 4

ROMFS/px4fmu_common/init.d/rc.interface

@@ -125,6 +125,11 @@ then
 	set MIXER_AUX none
 fi
 
+if [ $USE_IO == no ]
+then
+	set MIXER_AUX none
+fi
+
 if [ $MIXER_AUX != none -a $AUX_MODE != none ]
 then
 	#

ROMFS/px4fmu_common/init.d/rcS

@@ -321,59 +321,56 @@ then
 
 	set IO_PRESENT no
 
-	if [ $USE_IO == yes ]
+	#
+	# Check if PX4IO present and update firmware if needed
+	#
+	if [ -f /etc/extras/px4io-v2.bin ]
 	then
-		#
-		# Check if PX4IO present and update firmware if needed
-		#
-		if [ -f /etc/extras/px4io-v2.bin ]
+		set IO_FILE /etc/extras/px4io-v2.bin
+
+		if px4io checkcrc ${IO_FILE}
 		then
-			set IO_FILE /etc/extras/px4io-v2.bin
+			set IO_PRESENT yes
+		else
+			tone_alarm MLL32CP8MB
 
-			if px4io checkcrc ${IO_FILE}
+			if px4io start
 			then
-				set IO_PRESENT yes
-			else
-				tone_alarm MLL32CP8MB
-
-				if px4io start
+				# try to safe px4 io so motor outputs dont go crazy
+				if px4io safety_on
 				then
-					# try to safe px4 io so motor outputs dont go crazy
-					if px4io safety_on
-					then
-						# success! no-op
-					else
-						# px4io did not respond to the safety command
-						px4io stop
-					fi
+					# success! no-op
+				else
+					# px4io did not respond to the safety command
+					px4io stop
 				fi
+			fi
 
-				if px4io forceupdate 14662 ${IO_FILE}
+			if px4io forceupdate 14662 ${IO_FILE}
+			then
+				usleep 10000
+				if px4io checkcrc ${IO_FILE}
 				then
-					usleep 10000
-					if px4io checkcrc ${IO_FILE}
-					then
-						echo "PX4IO CRC OK after updating" >> $LOG_FILE
-						tone_alarm MLL8CDE
-
-						set IO_PRESENT yes
-					else
-						echo "PX4IO update failed" >> $LOG_FILE
-						tone_alarm ${TUNE_ERR}
-					fi
+					echo "PX4IO CRC OK after updating" >> $LOG_FILE
+					tone_alarm MLL8CDE
+
+					set IO_PRESENT yes
 				else
 					echo "PX4IO update failed" >> $LOG_FILE
-					tune_control play -m ${TUNE_ERR}
+					tone_alarm ${TUNE_ERR}
 				fi
+			else
+				echo "PX4IO update failed" >> $LOG_FILE
+				tune_control play -m ${TUNE_ERR}
 			fi
 		fi
-		unset IO_FILE
+	fi
+	unset IO_FILE
 
-		if [ $IO_PRESENT == no ]
-		then
-			echo "PX4IO not found" >> $LOG_FILE
-			tune_control play -m ${TUNE_ERR}
-		fi
+	if [ $USE_IO == yes -a $IO_PRESENT == no ]
+	then
+		echo "PX4IO not found" >> $LOG_FILE
+		tune_control play -m ${TUNE_ERR}
 	fi
 
 	#