Realtek Pin Function Controller

Required properties:
- compatible: "realtek,rts3903-pinctrl"
- reg: Address range of the pinctrl registers
- interrupt: Should contain the pinctrl interrupt number
- interrupt-parent: Should be the phandle for the interrupt controller
  that services interrupts for this device

Optional properties:
- wakeup-source: configure pinctrl as a wakeup source for suspend/resume

Please refer to pinctrl-bindings.txt in this directory for details of the
common pinctrl bindings used by client devices, including the meaning of the
phrase "pin configuration node".

Optional properties for pin configuration sub-nodes:
  - bias-pull-up: Enable weak pull-up.
  - bias-pull-down: Enable weak pull-down.
  - bias-disable: Enable no pull.

Example:

	pinctrl: pinctrl@0x18800000UL {
		#address-cells = <1>;
		#size-cells = <1>;
		ranges;
		compatible = "realtek,rts3903-pinctrl";
		reg = <0x18800000 0x10000>;
		interrupts = <BSP_IRQ_OTHERS>;
		interrupt-parent = <&cpuintc>;
		status = "disabled";
		wakeup-source;

		serial8250_default_mode: serial8250_default {
			default_mux {
				function = "uartfunc";
				groups = "uart1grp";
			};
		};

		audio_default_mode: audio_default {
			default_mux {
				function = "dmicfunc";
				groups = "dmicgrp";
			};
		};

		usbd_default_mode: usbd_default {
			default_mux {
				function = "usbdfunc";
				groups = "usbdgrp";
			};
		};

		eth_default_mode: eth_default {
			default_mux {
				function = "etnledfunc";
				groups = "etnled1grp", "rmiigrp";
			};
		};

		pwm_default_mode: pwm_default {
			default_mux {
				function = "pwmfunc";
				groups = "pwm0grp","pwm1grp",
					"pwm2grp","pwm3grp";
			};
		};

		isp_default_mode: isp_default {
				default_mux {
					function = "mcufunc";
					groups = "mcugrp";
				};
				default_cfg {
					pins = "GPIO50", "GPIO51";
					bias-disable;
				};
		};
	};
