ath5k: Add 802.11j 4.9GHz channels to allowed channels

Add the 802.11j (20MHz channel width) channels to the allowed channels. This
still does not enable 802.11j in ath5k since these frequencies are out of the
configured range. A later patch will deal with that.

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