usb: host: xhci-plat: add priv quirk for skip PHY initialization

Some DRD controllers (eg, dwc3 & cdns3) have PHY management at
their own driver to cover both device and host mode, so add one
priv quirk for such users to skip PHY management from HCD core.

Reviewed-by: Jun Li <jun.li@nxp.com>
Signed-off-by: Peter Chen <peter.chen@nxp.com>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Link: https://lore.kernel.org/r/20200918131752.16488-5-mathias.nyman@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>