[PATCH] orinoco: fix WE-21 buffer overflow

This patch fixes the Orinoco driver overflow issue with
WE-21.

Cc: Valdis Kletnieks <Valdis.Kletnieks@vt.edu>
Cc: Pavel Roskin <proski@gnu.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>