dt-bindings: gpio: fsl-imx-gpio: Add parsing of hogs

Allow parsing GPIO controller children nodes with GPIO hogs to fix
warning:

  arch/arm64/boot/dts/freescale/imx8mq-evk.dt.yaml: gpio@30240000: 'wl-reg-on' does not match any of the regexes: 'pinctrl-[0-9]+'
    From schema: Documentation/devicetree/bindings/gpio/fsl-imx-gpio.yaml
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20200825193536.7332-4-krzk@kernel.org

Documentation/devicetree/bindings/gpio/fsl-imx-gpio.yaml

@@ -53,6 +53,23 @@ properties:
 
   gpio-ranges: true
 
+patternProperties:
+  "^(hog-[0-9]+|.+-hog(-[0-9]+)?)$":
+    type: object
+    properties:
+      gpio-hog: true
+      gpios: true
+      input: true
+      output-high: true
+      output-low: true
+      line-name: true
+
+    required:
+      - gpio-hog
+      - gpios
+
+    additionalProperties: false
+
 required:
   - compatible
   - reg