media: lmedm04: Add missing usb_free_urb to free interrupt urb.

The interrupt urb is killed but never freed add the function

Signed-off-by: Malcolm Priestley <tvboxspy@gmail.com>
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>