dt-bindings: serial: vt8500-uart: convert to json-schema

Convert the VIA VT8500 and WonderMedia WM8xxx UART Controller to
newer DT schema. Created DT schema based on the .txt file which had
`compatible`, `reg`, `interrupts` and `clocks` as required properties.

Additions to the original binding
- changed the file name from vt8500-uart to via,vt8500-uart.yaml
- removed unnecessary alias from the example.

Signed-off-by: Kanak Shilledar <[e-mail]>
Acked-by: Alexey Charkov <[e-mail]>
Reviewed-by: Rob Herring (Arm) <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

Documentation/devicetree/bindings/serial/via,vt8500-uart.yaml

···
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/serial/via,vt8500-uart.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: VIA VT8500 and WonderMedia WM8xxx UART Controller
+
+maintainers:
+  - Alexey Charkov <[e-mail]>
+
+allOf:
+  - $ref: serial.yaml
+
+properties:
+  compatible:
+    enum:
+      - via,vt8500-uart # up to WM8850/WM8950
+      - wm,wm8880-uart  # for WM8880 and later
+
+  clocks:
+    maxItems: 1
+
+  interrupts:
+    maxItems: 1
+
+  reg:
+    maxItems: 1
+
+required:
+  - compatible
+  - clocks
+  - interrupts
+  - reg
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    serial@d8200000 {
+        compatible = "via,vt8500-uart";
+        reg = <0xd8200000 0x1040>;
+        interrupts = <32>;
+        clocks = <&clkuart0>;
+    };

Documentation/devicetree/bindings/serial/vt8500-uart.txt

···
-* VIA VT8500 and WonderMedia WM8xxx UART Controller
-
-Required properties:
-- compatible: should be "via,vt8500-uart" (for VIA/WonderMedia chips up to and
-	including WM8850/WM8950), or "wm,wm8880-uart" (for WM8880 and later)
-
-- reg: base physical address of the controller and length of memory mapped
-	region.
-
-- interrupts: hardware interrupt number
-
-- clocks: shall be the input parent clock phandle for the clock. This should
-	be the 24Mhz reference clock.
-
-Aliases may be defined to ensure the correct ordering of the uarts.
-
-Example:
-	aliases {
-		serial0 = &uart0;
-	};
-
-	uart0: serial@d8200000 {
-		compatible = "via,vt8500-uart";
-		reg = <0xd8200000 0x1040>;
-		interrupts = <32>;
-		clocks = <&clkuart0>;
-	};