Staging: w35und: wb35_probe() cleanup

Fix error handling in wb35_probe() function and clean it up a bit.

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>