Make code warnings-free with -pedantic, this should guard against more programming errors in the future

This removes a function that's no longer used, and inline specifiers
from include file (where they're useless anyway). This makes the whole
default project warnings-free with -Wall -pedantic.

Signed-off-by: Paul Fertser <fercerpav@gmail.com>
From what i can tell, this function didn't send anything useful to the frsky rx. The battery voltage is allready transmitted via sendVoltage(). I guess it can be removed.