cfg80211: reg: improve bad regulatory warning

There's a WARN_ON here but it says nothing, and the later
dump of the regdomain aren't usually printed. As a first
step, include the regdomain code in the WARN_ON message,
just like in other similar instances.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Link: https://lore.kernel.org/r/iwlwifi.20210618133832.853ffdd6c62b.I63e37b2ab184ee3653686e4df4dd23eb303687d2@changeidSigned-off-by: Johannes Berg <johannes.berg@intel.com>

net/wireless/reg.c

@@ -3975,7 +3975,9 @@ static int __regulatory_set_wiphy_regd(struct wiphy *wiphy,
 		 "wiphy should have REGULATORY_WIPHY_SELF_MANAGED\n"))
 		return -EPERM;
 
-	if (WARN(!is_valid_rd(rd), "Invalid regulatory domain detected\n")) {
+	if (WARN(!is_valid_rd(rd),
+		 "Invalid regulatory domain detected: %c%c\n",
+		 rd->alpha2[0], rd->alpha2[1])) {
 		print_regdomain_info(rd);
 		return -EINVAL;
 	}