wl1271: wakeup chip in op_conf_tx()

elp_wakeup() was missing in op_conf_tx() which caused wakeup problems in
power save. I forgot to add this part when porting the patch from wl1251.

Signed-off-by: Kalle Valo <kalle.valo@nokia.com>
Reviewed-by: Juuso Oikarinen <juuso.oikarinen@nokia.com>
Signed-off-by: Juuso Oikarinen <juuso.oikarinen@nokia.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>