Fix a small glitch noted by Yannick Cote.  There is no endpoint number
six, so if a (broken) host wrongly tried to change or read status of
that endpoint, the driver could access reserved register space.
Signed-off-by: NDavid Brownell <dbrownell@users.sourceforge.net>
Cc: Yannick Cote <yanick@yanos.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>