usb: misc: EHSET Test Fixture device driver for host compliance

An Embedded Host High-Speed Electrical Test (EHSET) test fixture is
used to initiate test modes on a host controller in order to perform
the high speed electrical testing procedure for USB-IF compliance.
When this test fixture is connected to a host, it can enumerate as
one of several selectable VID/PID pairs, each corresponding to one
of the following test modes:

* TEST_SE0_NAK
* TEST_J
* TEST_K
* TEST_PACKET
* HS_HOST_PORT_SUSPEND_RESUME
* SINGLE_STEP_GET_DEV_DESC
* SINGLE_STEP_SET_FEATURE

The USB EHSET procedure can be found here:
http://www.usb.org/developers/onthego/EHSET_v1.01.pdf



Signed-off-by: Manu Gautam <mgautam@codeaurora.org>
[jackp@codeaurora.org: imported from commit 073c9409 on codeaurora.org;
 minor cleanup and updated author email]
Signed-off-by: Jack Pham <jackp@codeaurora.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>