ath9k: fill led_pin before drv_start

Ensure that led pin is filled and set to OFF before starting
the driver. With recent changes, drv_start is being called even
before led_init is being completed. This is causing led is always
OFF on driver load when the interface is UP. This patch splits the
led init and fills the led pin before register hw.

Signed-off-by: Rajkumar Manoharan <rmanohar@qca.qualcomm.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>