cfg80211: remove wiphy_idx_valid

This is pretty much useless since get_wiphy_idx()
always returns true since it's always called with
a valid wiphy pointer.

Acked-by: Luis R. Rodriguez <mcgrof@do-not-panic.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index a19583c..5fbc8cd 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -8048,7 +8048,7 @@
 			goto nla_put_failure;
 	}
 
-	if (wiphy_idx_valid(request->wiphy_idx) &&
+	if (request->wiphy_idx != WIPHY_IDX_INVALID &&
 	    nla_put_u32(msg, NL80211_ATTR_WIPHY, request->wiphy_idx))
 		goto nla_put_failure;