Without temperature compensation the default is too narrow.

   Use the board supplied Power control macros, in the
   the board_peripheral_reset.

   This abstacts the polarity from the code. Therefore changes
   in signal sense can be made, just in the board config.

   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.

vmount: properly unadvertise uorb topics when stopping or re-configuring vmount. Othwerise subsequent advertise calls may fail (only ever witnessed for _mount_orientation_pub)

control_data needs to be able to be set to nullptr in case if the input
is already active. Otherwise the output will think there's always new
requests and reset it's state.

This avoids a busy-loop if the input is listening for vehicle commands and
the output publishes vehicle commands.

Issue: This conversion test failed with gcc 7.1.1 and clang 4.0.1:
```
ERROR [tests] conversion fail: input:  -0.8188, intermediate: -8187, result:  -0.8187
conv FAILED
Command 'tests' failed, returned -1
```

Fix: explicit rounding

-closes #7539