Staging: batman-adv: Move printk to simplified macros

Each general printk which is not informative by itself for a specific
batX device were moved to pr_(info|warning|err) as it provides an easy
interface which for example resolves the problem to add the prefix
"batman-adv: " before each line.

All information which is specific to a batX device will be printed using
a bat_(info|err|warning) macro to prefix it also with "batman-adv:
batX:" in each line.

Reported-by: Joe Perches <joe@perches.com>
Signed-off-by: Sven Eckelmann <sven.eckelmann@gmx.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>