dt-bindings: timer: Add fsl,timrot.yaml

Add fsl,timrot.yaml for i.MX23/i.MX28 timer.

Also add a generic fallback compatible string "fsl,timrot" for legacy
devices, which have existed for over 15 years.

Signed-off-by: Frank Li <[e-mail]>
Signed-off-by: Daniel Lezcano <[e-mail]>
Acked-by: Conor Dooley <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]

Documentation/devicetree/bindings/timer/fsl,timrot.yaml

···
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/timer/fsl,timrot.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Freescale MXS Timer
+
+maintainers:
+  - Frank Li <[e-mail]>
+
+properties:
+  compatible:
+    items:
+      - enum:
+          - fsl,imx23-timrot
+          - fsl,imx28-timrot
+      - const: fsl,timrot
+
+  reg:
+    maxItems: 1
+
+  interrupts:
+    items:
+      - description: irq for timer0
+      - description: irq for timer1
+      - description: irq for timer2
+      - description: irq for timer3
+
+  clocks:
+    maxItems: 1
+
+required:
+  - compatible
+  - reg
+  - interrupts
+  - clocks
+
+additionalProperties: false
+
+examples:
+  - |
+    timer: timer@80068000 {
+        compatible = "fsl,imx28-timrot", "fsl,timrot";
+        reg = <0x80068000 0x2000>;
+        interrupts = <48>, <49>, <50>, <51>;
+        clocks = <&clks 26>;
+    };