ath5k: dont use external sleep clock in AP mode

When using the external sleep clock in AP mode, the
TSF increments too quickly, causing beacon interval
to be much lower than it is supposed to be, resulting
in lots of beacon-not-ready interrupts.

This fixes http://bugzilla.kernel.org/show_bug.cgi?id=14802.
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/ath/ath5k/reset.c

@@ -1374,7 +1374,8 @@ int ath5k_hw_reset(struct ath5k_hw *ah, enum nl80211_iftype op_mode,
 	 * Set clocks to 32KHz operation and use an
 	 * external 32KHz crystal when sleeping if one
 	 * exists */
-	if (ah->ah_version == AR5K_AR5212)
+	if (ah->ah_version == AR5K_AR5212 &&
+	    ah->ah_op_mode != NL80211_IFTYPE_AP)
 		ath5k_hw_set_sleep_clock(ah, true);
 
 	/*