arm64: dts: Add more serial port nodes in APM X-Gene device tree

APM X-Gene Storm SoC supports 4 serial ports. This patch adds device nodes
for serial ports 1 to 3 (a device node for serial port 0 is already present
in the dts file).
This patch also sets the compatible property of serial nodes to "ns16550a".

Signed-off-by: Vinayak Kale <vkale@apm.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

arch/arm64/boot/dts/apm-mustang.dts

@@ -24,3 +24,7 @@
 		reg = < 0x1 0x00000000 0x0 0x80000000 >; /* Updated by bootloader */
 	};
 };
+
+&serial0 {
+	status = "ok";
+};

arch/arm64/boot/dts/apm-storm.dtsi

@@ -273,15 +273,49 @@
 		};
 
 		serial0: serial@1c020000 {
+			status = "disabled";
 			device_type = "serial";
-			compatible = "ns16550";
+			compatible = "ns16550a";
 			reg = <0 0x1c020000 0x0 0x1000>;
 			reg-shift = <2>;
 			clock-frequency = <10000000>; /* Updated by bootloader */
 			interrupt-parent = <&gic>;
 			interrupts = <0x0 0x4c 0x4>;
 		};
 
+		serial1: serial@1c021000 {
+			status = "disabled";
+			device_type = "serial";
+			compatible = "ns16550a";
+			reg = <0 0x1c021000 0x0 0x1000>;
+			reg-shift = <2>;
+			clock-frequency = <10000000>; /* Updated by bootloader */
+			interrupt-parent = <&gic>;
+			interrupts = <0x0 0x4d 0x4>;
+		};
+
+		serial2: serial@1c022000 {
+			status = "disabled";
+			device_type = "serial";
+			compatible = "ns16550a";
+			reg = <0 0x1c022000 0x0 0x1000>;
+			reg-shift = <2>;
+			clock-frequency = <10000000>; /* Updated by bootloader */
+			interrupt-parent = <&gic>;
+			interrupts = <0x0 0x4e 0x4>;
+		};
+
+		serial3: serial@1c023000 {
+			status = "disabled";
+			device_type = "serial";
+			compatible = "ns16550a";
+			reg = <0 0x1c023000 0x0 0x1000>;
+			reg-shift = <2>;
+			clock-frequency = <10000000>; /* Updated by bootloader */
+			interrupt-parent = <&gic>;
+			interrupts = <0x0 0x4f 0x4>;
+		};
+
 		phy1: phy@1f21a000 {
 			compatible = "apm,xgene-phy";
 			reg = <0x0 0x1f21a000 0x0 0x100>;