hal_usb_gadget sepolicy

Bug: 63669128
Test: Checked for avc denail messages.
Change-Id: I057b3cf9ccc945cb943b9cf60fc9cd6c023eddda
diff --git a/private/system_server.te b/private/system_server.te
index 1f39060..0589659 100644
--- a/private/system_server.te
+++ b/private/system_server.te
@@ -198,6 +198,7 @@
 hal_client_domain(system_server, hal_tv_cec)
 hal_client_domain(system_server, hal_tv_input)
 hal_client_domain(system_server, hal_usb)
+hal_client_domain(system_server, hal_usb_gadget)
 hal_client_domain(system_server, hal_vibrator)
 hal_client_domain(system_server, hal_vr)
 hal_client_domain(system_server, hal_weaver)