px4io: moving mixing to FMU side

Using mixers on the IO side had a remote benefit of being able to
override all control surfaces with a radio remote on a fixed wing.
This ended up not being used that much and since the original design
10 years ago (2011) we have been able to convince ourselves that the
overall system stability is at a level where this marginal benefit,
which is not present on multicopters, is not worth the hazzle.

Co-authored-by: Beat Küng <beat-kueng@gmx.net>
Co-authored-by: Daniel Agar <daniel@agar.ca>

ROMFS/px4fmu_common/init.d/rc.interface

@@ -17,6 +17,10 @@ set OUTPUT_DEV none
 set OUTPUT_AUX_DEV /dev/pwm_output1
 set OUTPUT_EXTRA_DEV /dev/pwm_output0
 
+# set these before starting the modules
+param set PWM_AUX_OUT ${PWM_AUX_OUT}
+param set PWM_MAIN_OUT ${PWM_OUT}
+
 #
 # If mount (gimbal) control is enabled and output mode is AUX, set the aux
 # mixer to mount (override the airframe-specific MIXER_AUX setting).
@@ -78,9 +82,16 @@ then
 		fi
 	fi
 
-	if [ $OUTPUT_MODE = io ]
+	#
+	# Start IO for PWM output or RC input if needed.
+	#
+	if [ $IO_PRESENT = yes ]
 	then
-		. ${R}etc/init.d/rc.io
+		if ! px4io start
+		then
+			echo "PX4IO start failed"
+			tune_control play -t 18 # PROG_PX4IO_ERR
+		fi
 	fi
 
 	if [ $OUTPUT_MODE = $OUTPUT_CMD -o $OUTPUT_MODE = io ]
@@ -91,17 +102,6 @@ then
 			tune_control play error
 		fi
 	fi
-
-	#
-	# Start IO for RC input if needed.
-	#
-	if [ $IO_PRESENT = yes ]
-	then
-		if [ $OUTPUT_MODE != io ]
-		then
-			. ${R}etc/init.d/rc.io
-		fi
-	fi
 fi
 
 if [ $MIXER != none -a $MIXER != skip ]
@@ -212,8 +212,6 @@ then
 	fi
 fi
 
-param set PWM_AUX_OUT ${PWM_AUX_OUT}
-
 if [ $OUTPUT_MODE = pwm_out -o $OUTPUT_MODE = io ]
 then
 	if [ $PWM_OUT != none ]
@@ -226,8 +224,6 @@ then
 	fi
 fi
 
-param set PWM_MAIN_OUT ${PWM_OUT}
-
 if [ $EXTRA_MIXER_MODE != none ]
 then