USB: UHCI: fix for suspend of virtual HP controller

HP's virtual UHCI host controller takes a long time to suspend
(several hundred microseconds), even when no devices are attached.
This provokes a warning message from uhci-hcd in the auto-stop case.

To prevent this from happening, this patch adds a test to avoid
performing an auto-stop when the wait_for_hp quirk flag is set.  The
controller will still suspend through the normal runtime PM mechanism.
And since that pathway includes a 1-ms delay, the slowness of the
virtual hardware won't matter.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Reported-and-tested-by: ZhenHua <zhen-hual@hp.com>
CC: <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>