Staging: w35und: move global wbsoft_enabled to struct wbsoft_priv

This is a preparational step for moving packet_came() to wb35rx.c().

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