arm: a37xx: espressobin: Explicitly enable eMMC node in -u-boot.dtsi

Official DT bindings for Espressobin have disabled eMMC node.

As U-Boot requires to have this node enabled by default, do it in
armada-3720-espressobin-u-boot.dtsi DTS file.

Signed-off-by: Pali Rohár <pali@kernel.org>
Reviewed-by: Stefan Roese <sr@denx.de>

arch/arm/dts/armada-3720-espressobin-u-boot.dtsi

@@ -21,3 +21,11 @@
 	};
 };
 #endif
+
+/*
+ * U-Boot requires to have this eMMC node by default in "okay" status. U-Boot
+ * at runtime changes status to "disabled" if eMMC is not present on the board.
+ */
+&sdhci0 {
+	status = "okay";
+};