This inversion matches the fixed sign in the commands generated
by the VTOL attitude controller.
This commit, combined with the previous commit, should have no effect.
For safety, it is recommended to check the direction of roll control
surfaces before flight.
- 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>