arm: mvebu: clearfog: fix boot from SD card

Enable gpio0 in SPL to allow the sdhci driver read the SD card-detect
signal.

Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Reviewed-by: Stefan Roese <sr@denx.de>
diff --git a/arch/arm/dts/armada-388-clearfog-u-boot.dtsi b/arch/arm/dts/armada-388-clearfog-u-boot.dtsi
index cf6c088..38e4f3d 100644
--- a/arch/arm/dts/armada-388-clearfog-u-boot.dtsi
+++ b/arch/arm/dts/armada-388-clearfog-u-boot.dtsi
@@ -12,6 +12,10 @@
 	u-boot,dm-spl;
 };
 
+&gpio0 {
+	u-boot,dm-spl;
+};
+
 &ahci0 {
 	u-boot,dm-spl;
 };