[RevoMini]: Fix an error in the RevoMini input channels.

I initially thought this fix was only for the prototype, but looking at OpenPilot's [RevoMini source code](http://reviews.openpilot.org/browse/~br=master/OpenPilot/flight/targets/boards/revolution/board_hw_defs.c?hb=true) it seems that it's a code error.



This effectively shifts channels, so that the first input pin to RM is also the PPM input pin.