dt-bindings: soc: Add fsl,imx23-digctl.yaml for i.MX23 and i.MX28

Add fsl,imx23-digctl.yaml for i.MX23 and i.MX28 to fix below CHECK_DTB
warning:

arch/arm/boot/dts/nxp/mxs/imx23-sansa.dtb: /apb@80000000/apbh-bus@80000000/digctl@8001c000:
    failed to match any schema with compatible: ['fsl,imx23-digctl']

Signed-off-by: Frank Li <Frank.Li@nxp.com>
Link: https://lore.kernel.org/r/20250528183549.694434-1-Frank.Li@nxp.com
Signed-off-by: Rob Herring (Arm) <robh@kernel.org>

Documentation/devicetree/bindings/soc/fsl/fsl,imx23-digctl.yaml

@@ -0,0 +1,53 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/soc/fsl/fsl,imx23-digctl.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Freescale mxs digctrl for i.MX23/i.MX28
+
+description: |
+  The digital control block provides overall control of various items within
+  the top digital block of the chip, including:
+    - Default first-level page table (DFLPT) controls
+    - HCLK performance counter
+    - Free-running microseconds counter
+    - Entropy control
+    - BIST controls for ARM Core and On-Chip RAM
+    - Chip Revision register
+    - USB loop back congtrol
+    - Other miscellaneous controls
+
+maintainers:
+  - Frank Li <Frank.Li@nxp.com>
+
+properties:
+  compatible:
+    oneOf:
+      - items:
+          - enum:
+              - fsl,imx28-digctl
+          - const: fsl,imx23-digctl
+      - const: fsl,imx23-digctl
+
+  reg:
+    maxItems: 1
+
+  interrupts:
+    maxItems: 1
+
+required:
+  - compatible
+  - reg
+  - interrupts
+
+additionalProperties: false
+
+examples:
+  - |
+    digctl@8001c000 {
+        compatible = "fsl,imx28-digctl", "fsl,imx23-digctl";
+        reg = <0x8001c000 0x2000>;
+        interrupts = <89>;
+    };
+