ARM: mvebu: Add Device Tree description of SDHCI for Armada 388 RD

The Device Tree description of SDHCI on Armada 388 RD board was
missing. This commit adds the node for it.
Signed-off-by: NGregory CLEMENT <gregory.clement@free-electrons.com>

arch/arm/boot/dts/armada-388-rd.dts

@@ -85,6 +85,16 @@
 				clock-frequency = <100000>;
 			};
 
+			sdhci@d8000 {
+				pinctrl-names = "default";
+				pinctrl-0 = <&sdhci_pins>;
+				broken-cd;
+				no-1-8-v;
+				wp-inverted;
+				bus-width = <8>;
+				status = "okay";
+			};
+
 			serial@12000 {
 				status = "okay";
 			};