ath9k: cleanup beacon parameters configuration

This patch configures the beacon timers with beacon interval
and beacon period passed through vif.bss_conf. Also cache the
currecnt beacon configuration which will be used to configure
the beacon timers when the driver triggers it after reset.

Signed-off-by: Vasanthakumar Thiagarajan <vasanth@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

diff --cc drivers/net/wireless/ath/ath9k/ath9k.h
Simple merge

diff --cc drivers/net/wireless/ath/ath9k/beacon.c
Simple merge