mac80211: make rate control Kconfig warning depend on mac80211

... Otherwise it is displayed when mac80211 isn't
even turned on, which is completely pointless.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

net/mac80211/Kconfig

@@ -78,7 +78,7 @@ config MAC80211_RC_DEFAULT
 endif
 
 comment "Some wireless drivers require a rate control algorithm"
-	depends on MAC80211_HAS_RC=n
+	depends on MAC80211 && MAC80211_HAS_RC=n
 
 config MAC80211_MESH
 	bool "Enable mac80211 mesh networking (pre-802.11s) support"