dt-bindings: serial: Convert snps,arc-uart to DT schema

Convert the Synopsys ARC UART binding to DT schema. Drop the "aliases"
portion which is not relevant to this schema.

Reviewed-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: "Rob Herring (Arm)" <robh@kernel.org>
Link: https://lore.kernel.org/r/20250507154909.1602497-1-robh@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Documentation/devicetree/bindings/serial/arc-uart.txt

@@ -1,25 +0,0 @@
-* Synopsys ARC UART : Non standard UART used in some of the ARC FPGA boards
-
-Required properties:
-- compatible		: "snps,arc-uart"
-- reg			: offset and length of the register set for the device.
-- interrupts		: device interrupt
-- clock-frequency	: the input clock frequency for the UART
-- current-speed		: baud rate for UART
-
-e.g.
-
-arcuart0: serial@c0fc1000 {
-	compatible = "snps,arc-uart";
-	reg = <0xc0fc1000 0x100>;
-	interrupts = <5>;
-	clock-frequency = <80000000>;
-	current-speed = <115200>;
-};
-
-Note: Each port should have an alias correctly numbered in "aliases" node.
-
-e.g.
-aliases {
-	serial0 = &arcuart0;
-};

Documentation/devicetree/bindings/serial/snps,arc-uart.yaml

@@ -0,0 +1,51 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/serial/snps,arc-uart.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Synopsys ARC UART
+
+maintainers:
+  - Vineet Gupta <vgupta@kernel.org>
+
+description:
+  Synopsys ARC UART is a non-standard UART used in some of the ARC FPGA boards.
+
+allOf:
+  - $ref: /schemas/serial/serial.yaml#
+
+properties:
+  compatible:
+    const: snps,arc-uart
+
+  reg:
+    maxItems: 1
+
+  interrupts:
+    maxItems: 1
+
+  clock-frequency:
+    description: the input clock frequency for the UART
+
+  current-speed:
+    description: baud rate for UART
+
+required:
+  - compatible
+  - reg
+  - interrupts
+  - clock-frequency
+  - current-speed
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    serial@c0fc1000 {
+        compatible = "snps,arc-uart";
+        reg = <0xc0fc1000 0x100>;
+        interrupts = <5>;
+        clock-frequency = <80000000>;
+        current-speed = <115200>;
+    };