ARM: dts: meson8b: ec100: enable the SDHC controller

EC-100 has built-in eMMC flash which is hard-wired to 3.3V VCC (which
means it's limited to high-speed MMC modes). Enable the SDHC controller
to access the contents of the eMMC flash.
Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Signed-off-by: Kevin Hilman <khilman@baylibre.com>
Link: https://lore.kernel.org/r/20200620163654.37207-3-martin.blumenstingl@googlemail.com

arch/arm/boot/dts/meson8b-ec100.dts

@@ -27,6 +27,11 @@ memory {
 		reg = <0x40000000 0x40000000>;
 	};
 
+	emmc_pwrseq: emmc-pwrseq {
+		compatible = "mmc-pwrseq-emmc";
+		reset-gpios = <&gpio BOOT_9 GPIO_ACTIVE_LOW>;
+	};
+
 	gpio-keys {
 		compatible = "gpio-keys-polled";
 		#address-cells = <1>;
@@ -299,6 +304,26 @@ &saradc {
 	vref-supply = <&vcc_1v8>;
 };
 
+&sdhc {
+	status = "okay";
+
+	pinctrl-0 = <&sdxc_c_pins>;
+	pinctrl-names = "default";
+
+	bus-width = <8>;
+	max-frequency = <50000000>;
+
+	cap-mmc-highspeed;
+	disable-wp;
+	non-removable;
+	no-sdio;
+
+	mmc-pwrseq = <&emmc_pwrseq>;
+
+	vmmc-supply = <&vcc_3v3>;
+	vqmmc-supply = <&vcc_3v3>;
+};
+
 &sdio {
 	status = "okay";