doc: usb: ci-hdrc-usb2: Add pinctrl properties for HSIC pin groups

For USB HSIC, the data and strobe pin needs to be pulled down
at default, we consider it as "idle" state. When the USB host
is ready to be used, the strobe pin needs to be pulled up,
we consider it as "active" state.
Signed-off-by: Peter Chen <peter.chen@nxp.com>

Documentation/devicetree/bindings/usb/ci-hdrc-usb2.txt

@@ -80,7 +80,10 @@ Optional properties:
   controller. It's expected that a mux state of 0 indicates device mode and a
   mux state of 1 indicates host mode.
 - mux-control-names: Shall be "usb_switch" if mux-controls is specified.
-- pinctrl-names: Names for optional pin modes in "default", "host", "device"
+- pinctrl-names: Names for optional pin modes in "default", "host", "device".
+  In case of HSIC-mode, "idle" and "active" pin modes are mandatory. In this
+  case, the "idle" state needs to pull down the data and strobe pin
+  and the "active" state needs to pull up the strobe pin.
 - pinctrl-n: alternate pin modes
 
 i.mx specific properties
@@ -111,3 +114,29 @@ Example:
 		mux-controls = <&usb_switch>;
 		mux-control-names = "usb_switch";
 	};
+
+Example for HSIC:
+
+	usb@2184400 {
+		compatible = "fsl,imx6q-usb", "fsl,imx27-usb";
+		reg = <0x02184400 0x200>;
+		interrupts = <0 41 IRQ_TYPE_LEVEL_HIGH>;
+		clocks = <&clks IMX6QDL_CLK_USBOH3>;
+		fsl,usbphy = <&usbphynop1>;
+		fsl,usbmisc = <&usbmisc 2>;
+		phy_type = "hsic";
+		dr_mode = "host";
+		ahb-burst-config = <0x0>;
+		tx-burst-size-dword = <0x10>;
+		rx-burst-size-dword = <0x10>;
+		pinctrl-names = "idle", "active";
+		pinctrl-0 = <&pinctrl_usbh2_idle>;
+		pinctrl-1 = <&pinctrl_usbh2_active>;
+		#address-cells = <1>;
+		#size-cells = <0>;
+
+		usbnet: smsc@1 {
+			compatible = "usb424,9730";
+			reg = <1>;
+		};
+	};