ath5k: Update PCU code

ath5k: Update PCU code

* In set_opmode don't handle antenna settings and preserve other STA_ID1 settings
(shouldn't matter because we call it during reset but it makes things cleaner)
Also set properly AP/ADHOC indicator flag on CFG while setting AP/ADHOC modes
and always enable key search mode.

* Properly set BSSID Mask during reset (cache it and reuse it durring set_associd)

* Update beacon_init to flush pending BMISS interrupts and handle setting of adhoc
beacon ATIM policy flag for ad-hoc mode. Also set TSF to 0 to start TSF increment
on AP mode. We need to handle sleep timers for AR5212 there + add support for PCF.

* Properly clean MIC key from keytable when TKIP is used (Bob is working on set_key
function etc so i leave it for now).

Tested on AR5212 (Hainan) and AR5413 and works fine

v2 Set PISR on AR5211+ and ISR on AR5210, got to sleep more ;-)

Changes-Licensed-under: ISC
Signed-Off-by: Nick Kossifidis <mickflemm@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>