USB: EHCI hooks for high speed electrical tests

EHCI hooks for high speed electrical tests of the root hub ports.

The expectation is that a usermode program actually triggers the test,
making the same control request it would make for an external hub.
Tests for peripheral upstream ports would issue a different request.
In all cases, the hardware needs re-initialization before it could
be used "normally" again (e.g. unplug/replug, rmmod/modprobe).

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>