batman-adv: Convert BATADV_PRINT_VID macro to function

The BATADV_PRINT_VID is not free of of possible side-effects. This can be
avoided when the the macro is converted to a simple inline function.

Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>