ath9k: remove unnecessary STATION mode check.

Remove unncessary STATION mode check in ath9k_bss_assoc_info() as
it is called only for STATION mode.

Signed-off-by: Senthil Balasubramanian <senthilkumar@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>