Staging: w35und: kill WBDEBUG and remove common.h header file

The only remaining thing in common.h header file is the WBDEBUG() macro which
is unconditionally defined as printk(). Kill the macro and remove the header
file.

Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>
Acked-by: Pavel Machek <pavel@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>