wpa_supplicant(hidl): remove unused parameter

The |ip| parameter for the P2P group started event is
unused. Despite that, we check if the |ip| is null.
And, if |ip| is null, we don't report the event up
to framework.

Note that
- we never actually report the |ip| to framework
- some listeners want to know about group start events, even
  when the |ip| is null.

Given the above, the null check is unnecessary. Since
the null check is unnecessary, the |ip| itself is
unnecessary.

Hence: remove the |ip| parameter for this event.

Bug: 37286961
Test: Compiles
Change-Id: I89c22d7513fd582e396057b771da33a13345f54b
diff --git a/wpa_supplicant/hidl/hidl.cpp b/wpa_supplicant/hidl/hidl.cpp
index 3acc7e2..1416799 100644
--- a/wpa_supplicant/hidl/hidl.cpp
+++ b/wpa_supplicant/hidl/hidl.cpp
@@ -474,9 +474,9 @@
 
 void wpas_hidl_notify_p2p_group_started(
     struct wpa_supplicant *wpa_s, const struct wpa_ssid *ssid, int persistent,
-    int client, const u8 *ip)
+    int client)
 {
-	if (!wpa_s || !ssid || !ip)
+	if (!wpa_s || !ssid)
 		return;
 
 	wpa_printf(
@@ -487,8 +487,7 @@
 	if (!hidl_manager)
 		return;
 
-	hidl_manager->notifyP2pGroupStarted(
-	    wpa_s, ssid, persistent, client, ip);
+	hidl_manager->notifyP2pGroupStarted(wpa_s, ssid, persistent, client);
 }
 
 void wpas_hidl_notify_p2p_group_removed(