mwifiex: MAC randomization should not be persistent

nl80211 provides the NL80211_SCAN_FLAG_RANDOM_ADDR for every scan
request that should be randomized; the absence of such a flag means we
should not randomize. However, mwifiex was stashing the latest
randomization request and *always* using it for future scans, even those
that didn't set the flag.

Let's zero out the randomization info whenever we get a scan request
without NL80211_SCAN_FLAG_RANDOM_ADDR. I'd prefer to remove
priv->random_mac entirely (and plumb the randomization MAC properly
through the call sequence), but the spaghetti is a little difficult to
unravel here for me.

Fixes: c2a8f0ff ("mwifiex: support random MAC address for scanning")
Cc: <stable@vger.kernel.org> # 4.9+
Signed-off-by: Brian Norris <briannorris@chromium.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

drivers/net/wireless/marvell/mwifiex/cfg80211.c

@@ -2547,9 +2547,11 @@ mwifiex_cfg80211_scan(struct wiphy *wiphy,
 			priv->random_mac[i] |= get_random_int() &
 					       ~(request->mac_addr_mask[i]);
 		}
+		ether_addr_copy(user_scan_cfg->random_mac, priv->random_mac);
+	} else {
+		eth_zero_addr(priv->random_mac);
 	}
 
-	ether_addr_copy(user_scan_cfg->random_mac, priv->random_mac);
 	user_scan_cfg->num_ssids = request->n_ssids;
 	user_scan_cfg->ssid_list = request->ssids;