[PATCH] Convert bcm43xx-softmac to use the ieee80211_is_valid_channel routine

The current version of bcm43xx-softmac uses local routines to check
if a channel is valid. As noted in the comments, these routines do
not take any regulatory information into account. This patch converts
the code to use the equivalent routine in ieee80211, which is being
converted to know about regulatory information.

Signed-Off-By: Larry Finger <Larry.Finger@lwfinger.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>