Staging: wlan-ng: Remove DBFENTER/DBFEXIT macros

Remove the ugly DBFENTER/DBFEXIT macros, which are only inserted to add "<---" and
"--->" at the function start/end at higher debug levels and which make the code
a lot less readable.

Signed-off-by: Moritz Muehlenhoff <jmm@debian.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>