[PATCH] USB: fix visor leaks

This patch fixes blatant leaks in visor driver and makes it report
mode sensible things in ->write_room (this is only needed if your visor
is a terminal though).

It is made to fit into 80 columns with a temporary variable.
Might even save a few instructions...

Signed-off-by: Pete Zaitcev <zaitcev@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>