USB2533 flex Hub

usb2533 HUB supports flex mode which allows swapping of upstream port with
one of the downstream port using I2C commands. This driver enables/disables
flex mode based on the USB mode (host/device).

Required properties :
- compatible : Must be "qcom,usb2533-flex-hub"
- reg: 7bit I2C slave address
- <supply-name>-supply: handle to the regulator device tree node.
        "supply-name" is "vbus" regulator to drive peripheral Vbus
	line in host mode.

Optional properties:
- qcom,hub-reset-gpio : This corresponds to GPIO that is used to drive USB HUB
  reset pin.
- qcom,usbeth-reset-gpio : This corresponds to GPIO that is used to drive
  reset of any other downstream device connected to HUB.
  GPIO flag represents whether ENB pin is active-high(0) or active-low(1).

Example :
	usb2533@2d {
		compatible = "qcom,usb2533-flex-hub";
		reg = <0x2d>;
		vbus-supply = <&usbeth_vbus_vreg>;
		pinctrl-names = "default";
		pinctrl-0 = <&usb2533_hub_reset>;
		qcom,hub-reset-gpio = <&tlmm 100 0>;
		qcom,usbeth-reset-gpio = <&ioexp_gpios 5 0>;
	};