RC00 had an active high VDD_5V_PERIPH_EN
   PC01 has an active low  VDD_5V_PERIPH_EN

   RC00 Test hardware did not use an LTC4417

   While RC00 HW is still in circulation you can build with
   PX4_FMUV5_RC00 defined and BOARD_HAS_LTC4417 undefined.

   The default is PX4_FMUV5_RC01 and BOARD_HAS_LTC4417 defined.