dt-bindings: pinctrl: imx: Support i.MX91 IOMUXC

i.MX91 and i.MX93 share similar design. They could share same dt-binding
doc, so rename fsl,imx93-pinctrl.yaml to fsl,imx9-pinctrl.yaml and add
i.MX91 compatible string

Signed-off-by: Peng Fan <[e-mail]>
Acked-by: Conor Dooley <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Linus Walleij <[e-mail]>

Documentation/devicetree/bindings/pinctrl/fsl,imx93-pinctrl.yaml Documentation/devicetree/bindings/pinctrl/fsl,imx9-pinctrl.yaml

···
 # SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
 %YAML 1.2
 ---
-$id: http://devicetree.org/schemas/pinctrl/fsl,imx93-pinctrl.yaml#
+$id: http://devicetree.org/schemas/pinctrl/fsl,imx9-pinctrl.yaml#
 $schema: http://devicetree.org/meta-schemas/core.yaml#
 
-title: Freescale IMX93 IOMUX Controller
+title: Freescale IMX9 IOMUX Controller
 
 maintainers:
   - Peng Fan <[e-mail]>
···
 
 properties:
   compatible:
-    const: fsl,imx93-iomuxc
+    enum:
+      - fsl,imx91-iomuxc
+      - fsl,imx93-iomuxc
 
   reg:
     maxItems: 1