ath5k: honor FIF_BCN_PRBRESP_PROMISC in STA mode

We were setting RX_FILTER_BEACON even after entering STA mode,
which leads to a lot of unnecessary wakeups.  This should fix the
bug "Ath5k driver has too many interrupts per second at idle" at
http://bugzilla.kernel.org/show_bug.cgi?id=11749.

Signed-off-by: Bob Copeland <me@bobcopeland.com>
Acked-by: Nick Kossifidis <mickflemm@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/ath5k/base.c

@@ -2942,10 +2942,8 @@ static void ath5k_configure_filter(struct ieee80211_hw *hw,
 		sc->opmode != NL80211_IFTYPE_MESH_POINT &&
 		test_bit(ATH_STAT_PROMISC, sc->status))
 		rfilt |= AR5K_RX_FILTER_PROM;
-	if (sc->opmode == NL80211_IFTYPE_STATION ||
-		sc->opmode == NL80211_IFTYPE_ADHOC) {
+	if (sc->opmode == NL80211_IFTYPE_ADHOC)
 		rfilt |= AR5K_RX_FILTER_BEACON;
-	}
 
 	/* Set filters */
 	ath5k_hw_set_rx_filter(ah,rfilt);