Bluetooth: Host: Fix not sending Service Changed indication

gatt_unregister() clears handles if those were auto-assigned by host.
This resulted in Service Changed indication not beding sent since
call to sc_indicate() pass already cleared handles.

This was affecting GATT/SR/GAS/BV-01-C and GATT/SR/GAS/BV-07-C test
cases.

Signed-off-by: Szymon Janc <szymon.janc@codecoup.pl>

subsys/bluetooth/host/gatt.c

@@ -1743,10 +1743,18 @@ int bt_gatt_service_register(struct bt_gatt_service *svc)
 
 int bt_gatt_service_unregister(struct bt_gatt_service *svc)
 {
+	uint16_t sc_start_handle;
+	uint16_t sc_end_handle;
 	int err;
 
 	__ASSERT(svc, "invalid parameters\n");
 
+	/* gatt_unregister() clears handles when those were auto-assigned
+	 * by host
+	 */
+	sc_start_handle = svc->attrs[0].handle;
+	sc_end_handle = svc->attrs[svc->attr_count - 1].handle;
+
 	k_sched_lock();
 
 	err = gatt_unregister(svc);
@@ -1761,8 +1769,7 @@ int bt_gatt_service_unregister(struct bt_gatt_service *svc)
 		return 0;
 	}
 
-	sc_indicate(svc->attrs[0].handle,
-		    svc->attrs[svc->attr_count - 1].handle);
+	sc_indicate(sc_start_handle, sc_end_handle);
 
 	db_changed();