staging: most: hdm-usb: remove completion object

Waiting for the urb_compl object to complete evaluates always as false.
This patch removes this unnecessary completion object.

Signed-off-by: Andrey Shvetsov <andrey.shvetsov@k2l.de>
Signed-off-by: Christian Gromm <christian.gromm@microchip.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>