usb: gadget: f_subset: replace PTR_RET with PTR_ERR_OR_ZERO

PTR_RET is deprecated. Do not recommend its usage anymore.
Use PTR_ERR_OR_ZERO instead.

Signed-off-by: Duan Jiong <duanj.fnst@cn.fujitsu.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>
diff --git a/drivers/usb/gadget/f_subset.c b/drivers/usb/gadget/f_subset.c
index df4a0dcb..1ea8baf 100644
--- a/drivers/usb/gadget/f_subset.c
+++ b/drivers/usb/gadget/f_subset.c
@@ -276,7 +276,7 @@
 	}
 
 	net = gether_connect(&geth->port);
-	return PTR_RET(net);
+	return PTR_ERR_OR_ZERO(net);
 }
 
 static void geth_disable(struct usb_function *f)