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.