Changed name of mixer to be shorter

ROMFS/px4fmu_common/init.d/airframes/50003_aion_robotics_r1_rover

@@ -68,6 +68,6 @@ fi
 set MAV_TYPE 10
 
 # Set mixer
-set MIXER generic_differential_rover
+set MIXER generic_diff_rover
 
 set PWM_MAIN_REV2 1

ROMFS/px4fmu_common/mixers/CMakeLists.txt

@@ -52,7 +52,7 @@ px4_add_romfs_files(
 	firefly6.main.mix
 	fw_generic_wing.main.mix
 	FX79.main.mix
-	generic_differential_rover.main.mix
+	generic_diff_rover.main.mix
 	hexa_cox.main.mix
 	hexa_+.main.mix
 	hexa_x.main.mix