selftests: add test for USB over IP driver

Add test for USB over IP driver. This test runs several tests on a device
specified in the -b <busid> argument and path to the usbip tools.

usbip_test.sh -b <busid> -p <usbip tools path>

e.g:
cd tools/testing selftests/drivers/usb/usbip
sudo ./usbip_test.sh -b 3-10.2 -p <yoursrctree>/tools/usb/usbip

This test should be run as root and user should build usbip tools before
running the test.

The usbip test isn't included in the Kselftest run as it requires user to
specify a device to run tests on.

Signed-off-by: Shuah Khan (Samsung OSG) <shuah@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>