Broadcom IPROC SDHCI controller

This file documents differences between the core properties described
by mmc.txt and the properties that represent the IPROC SDHCI controller.

Required properties:
- compatible : Should be one of the following
	       "brcm,bcm2835-sdhci"
	       "brcm,bcm2711-emmc2"
	       "brcm,sdhci-iproc-cygnus"
	       "brcm,sdhci-iproc"

Use brcm2835-sdhci for the eMMC controller on the BCM2835 (Raspberry Pi) and
bcm2711-emmc2 for the additional eMMC2 controller on BCM2711.

Use sdhci-iproc-cygnus for Broadcom SDHCI Controllers
restricted to 32bit host accesses to SDHCI registers.

Use sdhci-iproc for Broadcom SDHCI Controllers that allow standard
8, 16, 32-bit host access to SDHCI register.

- clocks : The clock feeding the SDHCI controller.

Optional properties:
  - sdhci,auto-cmd12: specifies that controller should use auto CMD12.

Example:

sdhci0: sdhci@18041000 {
	compatible = "brcm,sdhci-iproc-cygnus";
	reg = <0x18041000 0x100>;
	interrupts = <GIC_SPI 108 IRQ_TYPE_LEVEL_HIGH>;
	clocks = <&lcpll0_clks BCM_CYGNUS_LCPLL0_SDIO_CLK>;
	bus-width = <4>;
	sdhci,auto-cmd12;
	no-1-8-v;
};