Put payload outputs for AERT mixer onto right actuator group

ROMFS/px4fmu_common/mixers/FMU_AERT.mix

@@ -64,21 +64,22 @@ O:      10000  10000      0 -10000  10000
 S: 0 3      0  20000 -10000 -10000  10000
 
 
-Gimbal / flaps / payload mixer for last four channels
+Gimbal / flaps / payload mixer for last four channels,
+using the payload control group
 -----------------------------------------------------
 
 M: 1
 O:      10000  10000      0 -10000  10000
-S: 0 4  10000  10000      0 -10000  10000
+S: 2 0  10000  10000      0 -10000  10000
 
 M: 1
 O:      10000  10000      0 -10000  10000
-S: 0 5  10000  10000      0 -10000  10000
+S: 2 1  10000  10000      0 -10000  10000
 
 M: 1
 O:      10000  10000      0 -10000  10000
-S: 0 6  10000  10000      0 -10000  10000
+S: 2 2  10000  10000      0 -10000  10000
 
 M: 1
 O:      10000  10000      0 -10000  10000
-S: 0 7  10000  10000      0 -10000  10000
+S: 2 3  10000  10000      0 -10000  10000