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>

msg/px4io_status.msg

@@ -6,49 +6,38 @@ float32 voltage_v		# Servo rail voltage in volts
 float32 rssi_v			# RSSI pin voltage in volts
 
 # PX4IO status flags (PX4IO_P_STATUS_FLAGS)
-bool status_outputs_armed
-bool status_override
-bool status_rc_ok
-bool status_rc_ppm
-bool status_rc_dsm
-bool status_rc_sbus
-bool status_fmu_ok
-bool status_raw_pwm
-bool status_mixer_ok
 bool status_arm_sync
-bool status_init_ok
 bool status_failsafe
-bool status_safety_off
 bool status_fmu_initialized
+bool status_fmu_ok
+bool status_init_ok
+bool status_outputs_armed
+bool status_raw_pwm
+bool status_rc_ok
+bool status_rc_dsm
+bool status_rc_ppm
+bool status_rc_sbus
 bool status_rc_st24
 bool status_rc_sumd
+bool status_safety_off
 
 # PX4IO alarms (PX4IO_P_STATUS_ALARMS)
-bool alarm_vbatt_low
-bool alarm_temperature
-bool alarm_servo_current
-bool alarm_acc_current
-bool alarm_fmu_lost
-bool alarm_rc_lost
 bool alarm_pwm_error
-bool alarm_vservo_fault
+bool alarm_rc_lost
 
 # PX4IO arming (PX4IO_P_SETUP_ARMING)
-bool arming_io_arm_ok
+bool arming_failsafe_custom
 bool arming_fmu_armed
 bool arming_fmu_prearmed
-bool arming_manual_override_ok
-bool arming_failsafe_custom
-bool arming_inair_restart_ok
-bool arming_always_pwm_enable
-bool arming_rc_handling_disabled
-bool arming_lockdown
 bool arming_force_failsafe
+bool arming_io_arm_ok
+bool arming_lockdown
 bool arming_termination_failsafe
-bool arming_override_immediate
 
+uint16[8] pwm
+uint16[8] pwm_disarmed
+uint16[8] pwm_failsafe
 
-int16[8] actuators
-uint16[8] servos
+uint16[8] pwm_rate_hz
 
 uint16[18] raw_inputs