ARM: dts: AM33XX: Add basic pinctrl device tree data

Adds basic pinctrl device tree data for AM33XX family of devices.
This patch is based on the pinctrl-single driver.
Signed-off-by: AnilKumar Ch <anilkumar@ti.com>
Signed-off-by: Benoit Cousson <b-cousson@ti.com>

arch/arm/boot/dts/am33xx.dtsi

@@ -55,6 +55,15 @@ mpu {
 		};
 	};
 
+	am33xx_pinmux: pinmux@44e10800 {
+		compatible = "pinctrl-single";
+		reg = <0x44e10800 0x0238>;
+		#address-cells = <1>;
+		#size-cells = <0>;
+		pinctrl-single,register-width = <32>;
+		pinctrl-single,function-mask = <0x7f>;
+	};
+
 	/*
 	 * XXX: Use a flat representation of the AM33XX interconnect.
 	 * The real AM33XX interconnect network is quite complex.Since