tools: usb: usbip_device_driver: prefer 'unsigned int' to 'unsigned'

Fixup a coding style issue

Signed-off-by: Elad Wexler <elad.wexler@gmail.com>
Acked-by: Shuah Khan <shuahkh@osg.samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>