wifi-scripts: return the interface-creation result from wdev_add

wdev_add() dropped the wdev_create() result, so every caller's error check
was dead and an nl80211 NEW_INTERFACE failure was silently ignored (hostapd
and wpa_supplicant then proceeded on a missing netdev with stale MLD
bookkeeping). Return the result.

Signed-off-by: Felix Fietkau <nbd@nbd.name>

package/network/config/wifi-scripts/files/usr/share/hostap/common.uc

@@ -298,8 +298,7 @@ const phy_proto = {
 	},
 
 	wdev_add: function(name, data) {
-		let phydev = this;
-		wdev_create(this.phy, name, {
+		return wdev_create(this.phy, name, {
 			...data,
 			radio: this.radio,
 		});