Interworking: Remove unused variable warnings

This patch removes these warnings.

interworking.c: In function 'interworking_credentials_available_3gpp':
interworking.c:1330:6: warning: unused variable 'ret' [-Wunused-variable]
interworking.c:1329:19: warning: unused variable 'cred' [-Wunused-variable]

Signed-hostap: Masashi Honma <masashi.honma@gmail.com>

wpa_supplicant/interworking.c

@@ -1326,10 +1326,11 @@ fail:
 static struct wpa_cred * interworking_credentials_available_3gpp(
 	struct wpa_supplicant *wpa_s, struct wpa_bss *bss)
 {
-	struct wpa_cred *cred, *selected = NULL;
+	struct wpa_cred *selected = NULL;
+#ifdef INTERWORKING_3GPP
+	struct wpa_cred *cred;
 	int ret;
 
-#ifdef INTERWORKING_3GPP
 	if (bss->anqp == NULL || bss->anqp->anqp_3gpp == NULL)
 		return NULL;