cfg80211: don't drop p2p probe responses

Commit 0a35d36 ("cfg80211: Use capability info to detect mesh beacons")
assumed that probe response with both ESS and IBSS bits cleared
means that the frame was sent by a mesh sta.

However, these capabilities are also being used in the p2p_find phase,
and the mesh-validation broke it.

Rename the WLAN_CAPABILITY_IS_MBSS macro, and verify that mesh ies
exist before assuming this frame was sent by a mesh sta.

Signed-off-by: Eliad Peller <eliad@wizery.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/include/linux/ieee80211.h b/include/linux/ieee80211.h
index b2eee58..bf56b6f 100644
--- a/include/linux/ieee80211.h
+++ b/include/linux/ieee80211.h
@@ -1003,8 +1003,12 @@
 #define WLAN_CAPABILITY_ESS		(1<<0)
 #define WLAN_CAPABILITY_IBSS		(1<<1)
 
-/* A mesh STA sets the ESS and IBSS capability bits to zero */
-#define WLAN_CAPABILITY_IS_MBSS(cap)	\
+/*
+ * A mesh STA sets the ESS and IBSS capability bits to zero.
+ * however, this holds true for p2p probe responses (in the p2p_find
+ * phase) as well.
+ */
+#define WLAN_CAPABILITY_IS_STA_BSS(cap)	\
 	(!((cap) & (WLAN_CAPABILITY_ESS | WLAN_CAPABILITY_IBSS)))
 
 #define WLAN_CAPABILITY_CF_POLLABLE	(1<<2)