usb: xhci: set SSIC port unused only if xhci_suspend succeeds

XHCI_SSIC_PORT_UNUSED quirk was applied to the xHCI host controllers
in some Intel SoC chips.  With this quirk applied, SSIC port is set
to "unused" prior to xhci_suspend(). This may cause problem if host
fails to suspend.  In this case, the port is set to unused without
host further entering D3, and the port will not be usable anymore.

Cc: stable@vger.kernel.org
Signed-off-by: Zhuang Jin Can <jin.can.zhuang@intel.com>
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>