[wpa_supplicant] Remove null checks for URL in deauth imminent

The URL in deauth imminent message is optional and can be null.
Remove all null checks of the URL to allow the framework to
process deauth imminent notifications with no reason URLs.

Bug: 171320371
Test: Compiles. Not in use (yet)
Change-Id: I916d1d08f3bab033c4cf5361d0c77bef5fac6d67
diff --git a/wpa_supplicant/notify.c b/wpa_supplicant/notify.c
index 3cd85aa..e096579 100644
--- a/wpa_supplicant/notify.c
+++ b/wpa_supplicant/notify.c
@@ -1007,7 +1007,7 @@
 						const char *url)
 {
 #ifdef CONFIG_HS20
-	if (!wpa_s || !url)
+	if (!wpa_s)
 		return;
 
 	wpas_hidl_notify_hs20_rx_deauth_imminent_notice(wpa_s, code, reauth_delay,