* MTK MMC controller

The MTK  MSDC can act as a MMC controller
to support MMC, SD, and SDIO types of memory cards.

This file documents differences between the core properties in mmc.txt
and the properties used by the msdc driver.

Required properties:
- compatible: Should be "mediatek,mt8173-mmc","mediatek,mt8135-mmc"
- interrupts: Should contain MSDC interrupt number
- clocks: MSDC source clock, HCLK
- clock-names: "source", "hclk"
- pinctrl-names: should be "default", "state_uhs"
- pinctrl-0: should contain default/high speed pin ctrl
- pinctrl-1: should contain uhs mode pin ctrl
- vmmc-supply: power to the Core
- vqmmc-supply: power to the IO

Examples:
mmc0: mmc@11230000 {
	compatible = "mediatek,mt8173-mmc", "mediatek,mt8135-mmc";
	reg = <0 0x11230000 0 0x108>;
	interrupts = <GIC_SPI 39 IRQ_TYPE_LEVEL_LOW>;
	vmmc-supply = <&mt6397_vemc_3v3_reg>;
	vqmmc-supply = <&mt6397_vio18_reg>;
	clocks = <&pericfg CLK_PERI_MSDC30_0>, <&topckgen CLK_TOP_MSDC50_0_H_SEL>;
	clock-names = "source", "hclk";
	pinctrl-names = "default", "state_uhs";
	pinctrl-0 = <&mmc0_pins_default>;
	pinctrl-1 = <&mmc0_pins_uhs>;
};