UPSTREAM: xHCI: add cmd_ring_state

UPSTREAM: xHCI: add cmd_ring_state

commit c181bc5b5d5c79b71203cd10cef97f802fb6f9c1 upstream.

Adding cmd_ring_state for command ring. It helps to verify
the current command ring state for controlling the command
ring operations.

This patch should be backported to kernels as old as 3.0.  The commit
7ed603ecf8b68ab81f4c83097d3063d43ec73bb8 "xhci: Add an assertion to
check for virt_dev=0 bug." papers over the NULL pointer dereference that
I now believe is related to a timed out Set Address command.  This (and
the four patches that follow it) contain the real fix that also allows
VIA USB 3.0 hubs to consistently re-enumerate during the plug/unplug
stress tests.

Signed-off-by: Elric Fu <elricfu1@gmail.com>
Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Tested-by: Miroslav Sabljic <miroslav.sabljic@avl.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from commit 1976fffe9dc839e9d25c903a65723600f7641a50)

BUG=None
TEST=Together with other cherry-picks: run BVT trybots on all platforms,
manually confirm that USB network/storage/input devices still work
(including across suspend/resume)

Change-Id: Ib07ee436e4288ddcd9d13776ff8bcd2c44d99217
Signed-off-by: Julius Werner <jwerner@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/46058
Reviewed-by: Vincent Palatin <vpalatin@chromium.org>