usb: gadget: zero: fix error return code in zero_bind()

Fix to return a negative error code from the error handling
case instead of 0, as done elsewhere in this function.

Introduced by commit cf9a08ae
(usb: gadget: convert source sink and loopback to new function interface)
Acked-by: Michal Nazarewicz <mina86@mina86.com>
Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Signed-off-by: Felipe Balbi <balbi@ti.com>

drivers/usb/gadget/zero.c

@@ -284,12 +284,16 @@ static int __init zero_bind(struct usb_composite_dev *cdev)
 	ss_opts->bulk_buflen = gzero_options.bulk_buflen;
 
 	func_ss = usb_get_function(func_inst_ss);
-	if (IS_ERR(func_ss))
+	if (IS_ERR(func_ss)) {
+		status = PTR_ERR(func_ss);
 		goto err_put_func_inst_ss;
+	}
 
 	func_inst_lb = usb_get_function_instance("Loopback");
-	if (IS_ERR(func_inst_lb))
+	if (IS_ERR(func_inst_lb)) {
+		status = PTR_ERR(func_inst_lb);
 		goto err_put_func_ss;
+	}
 
 	lb_opts = container_of(func_inst_lb, struct f_lb_opts, func_inst);
 	lb_opts->bulk_buflen = gzero_options.bulk_buflen;