net: usb: rtl8150: fix memory leak on usb_submit_urb() failure

In the Linux kernel, the following vulnerability has been resolved:

net: usb: rtl8150: fix memory leak on usb_submit_urb() failure

In async_set_registers(), when usb_submit_urb() fails, the allocated async_req structure and URB are not freed, causing a memory leak.

The completion callback async_set_reg_cb() is responsible for freeing these allocations, but it is only called after the URB is successfully submitted and completes (successfully or with error). If submission fails, the callback never runs and the memory is leaked.

Fix this by freeing both the URB and the request structure in the error path when usb_submit_urb() fails.