usb: xhci: add a quirk bit for ssic port unused

Two workarounds introduced by commit b8cb91e0 ("xhci: Workaround
for PME stuck issues in Intel xhci") and commit abce329c ("xhci:
Workaround to get D3 working in Intel xHCI") share a single quirk bit
XHCI_PME_STUCK_QUIRK. These two workarounds actually are different and
might happen on different hardwares. Need to separate them by adding a
quirk bit for the later.

Cc: stable@vger.kernel.org
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>