ARM64: zynqmp: Use zynqmp specific compatible string for gpio

The patch:
"gpio: Added support to Zynq Ultrascale+ MPSoC"
(sha1: bdf7a4ae37)
added zynqmp specific features. This patch is switching the driver to
use the zynqmp compatible string.
Also enable the driver for ep108 platform.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>

arch/arm64/boot/dts/xilinx/zynqmp-ep108.dts

@@ -42,6 +42,10 @@ phy0: phy@0{
 	};
 };
 
+&gpio {
+	status = "okay";
+};
+
 &sata {
 	status = "okay";
 	ceva,broken-gen2;

arch/arm64/boot/dts/xilinx/zynqmp.dtsi

@@ -163,7 +163,7 @@ uart1: serial@ff010000 {
 		};
 
 		gpio: gpio@ff0a0000 {
-			compatible = "xlnx,zynq-gpio-1.0";
+			compatible = "xlnx,zynqmp-gpio-1.0";
 			status = "disabled";
 			#gpio-cells = <0x2>;
 			clocks = <&misc_clk>;