doc: dt: bindings: usb: dwc3: Update entries for disabling SS instances in park mode

This patch updates the documentation with the information related
to the quirks that needs to be added for disabling all SuperSpeed XHCI
instances in park mode.

Cc: Dongjin Kim <tobetter@gmail.com>
Cc: Jianxin Pan <jianxin.pan@amlogic.com>
Cc: Thinh Nguyen <thinhn@synopsys.com>
Cc: Jun Li <lijun.kernel@gmail.com>
Reported-by: Tim <elatllat@gmail.com>
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Felipe Balbi <balbi@kernel.org>