staging: gdm724x: gdm_usb: Remove ignored value

The value assigned to ret will be overwritten before it could be read in a
future iteration of the loop. Removing the unnecessary assignment.

Signed-off-by: Luis de Bethencourt <luisbg@osg.samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>