ath5k: No need to save/restore staid flags on reset

 * Since we set antenna flags on phy init and ack bitrate
 mode on pcu init, there is no need to save/restore sta_id
 flags on ath5k_hw_reset. Also we don't need to re-set our
 mac address because it's not affected by resets.

 Signed-off-by: Nick Kossifidis <mickflemm@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>