ROMFS: clean up quad x tailsitter mixer files

- use mixer for the simulation to the sitl mixer dir
- do not use virtual elevator in the mixer for the real vehicle

Signed-off-by: Roman <bapstroman@gmail.com>

ROMFS/px4fmu_common/mixers/CMakeLists.txt

@@ -75,7 +75,6 @@ px4_add_romfs_files(
 	quad_x_can.main.mix
 	quad_x.main.mix
 	quad_x_vtol.main.mix
-	quad_x_vtol_sim.main.mix
 	stampede.main.mix
 	tri_y_yaw-.main.mix
 	tri_y_yaw+.main.mix

ROMFS/px4fmu_common/mixers/quad_x_vtol.main.mix

@@ -6,8 +6,6 @@ are mixed 100%.
 
 R: 4x 10000 10000 10000 0
 
-Z:
-
 # left elevon
 M: 2
 S: 1 0  5000  5000      0 -10000  10000
@@ -17,7 +15,3 @@ S: 1 1  5000  5000      0 -10000  10000
 M: 2
 S: 1 0   5000   5000    0 -10000  10000
 S: 1 1  -5000  -5000    0 -10000  10000
-
-# mixer for the virtual elevator
-M: 1
-S: 1 1   10000   10000    0 -10000  10000