usb: misc: usb3503: Adding device tree entry 'disabled-ports'

This patch is to add a property 'disabled-ports' representing the unused port
of USB3503. USB3503 can support up to 3 USB host port and each ports can be
controlled to be enabled or disabled. Do not describe this property if all
ports must be enabled.

You can represent the ports to disable in the device tree.

	usb3503@08{
		...
		disabled-ports = <2 3>;
		...
	};

Signed-off-by: Dongjin Kim <tobetter@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>