USB: uas: Implement the new shutdown callback

A standard implementation of shutdown callback has been implemented
for USB drivers. Since the UAS driver implements a shutdown callback
this patch enables it to use the new standard implementation.

Signed-off-by: Kerem Karabay <kekrby@gmail.com>
Signed-off-by: Aditya Garg <gargaditya08@live.com>
Link: https://lore.kernel.org/r/E3A502A9-6572-4F1B-9EB2-2F6F0C4E6EA8@live.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>