Replace BCD2BIN and BIN2BCD macros with inline functions

In the process, also remove backward-compatiblity macros BIN_TO_BCD and
BCD_TO_BIN and update the sole board using them to use the new bin2bcd
and bcd2bin instead

Signed-off-by: Albin Tonnerre <albin.tonnerre@free-electrons.com>
Acked-by: Stefan Roese <sr@denx.de>
Acked-by: Detlev Zundel <dzu@denx.de>