b43/b43legacy: fix radio LED initialization

Fix condition in which radio LED did not initialize correctly, and remove
4 compilation warnings.

After the recent changes in rfkill, the radio LED used by b43/b43legacy
did not always initialize correctly.

Both b43 and b43legacy used the deprecated variable radio_enabled in
struct ieee80211_conf.

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