mac80211: increase U-APSD max service period length

Deliver up to 128 frames during service period instead of 8 if
unlimited is specified by the client during association.
8 was just an arbitrary value; so is 128 since unlimited can
be any number.

However for large traffic bursts, increasing this value looks
reasonable. Also, it seems that a few certification tests
expect more frames to be delivered during SP.

Signed-off-by: Andrei Otcheretianski <andrei.otcheretianski@intel.com>
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/sta_info.c

@@ -1531,7 +1531,7 @@ void ieee80211_sta_ps_deliver_uapsd(struct sta_info *sta)
 		break;
 	case 0:
 		/* XXX: what is a good value? */
-		n_frames = 8;
+		n_frames = 128;
 		break;
 	}