ath5k: several off by one range checks

There are several places that use > ARRAY_SIZE() instead of
>= ARRAY_SIZE().

Signed-off-by: Dan Carpenter <error27@gmail.com>
Acked-by: Bob Copeland <me@bobcopeland.com>
Acked-by: Bruno Randolf <br1@einfach.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>