cfg80211: ignore supported rates for nonexistant bands on scan

Fixes wpa_supplicant p2p_find on 5GHz-only devices

Signed-off-by: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index e20c27f..138dc3b 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -5349,6 +5349,10 @@
 				err = -EINVAL;
 				goto out_free;
 			}
+
+			if (!wiphy->bands[band])
+				continue;
+
 			err = ieee80211_get_ratemask(wiphy->bands[band],
 						     nla_data(attr),
 						     nla_len(attr),