ar9170: remove deprecated code

This patch removes code (deprecated by "cfg80211: add rfkill support" )

main.c: In function 'ar9170_op_config':
main.c:1306: warning: '__IEEE80211_CONF_CHANGE_RADIO_ENABLED'
is deprecated (declared at include/net/mac80211.h:551)

and a useless device state.

Signed-off-by: Christian Lamparter <chunkeey@web.de>
Signed-off-by: John W. Linville <linville@tuxdriver.com>