pinctrl: mxs: Remove undocumented 'fsl,mxs-gpio' property

The 'fsl,mxs-gpio' property is not documented in gpio-mxs.yaml, but
the imx23 and imx28 dtsi describe the gpios as:

compatible = "fsl,imx28-gpio", "fsl,mxs-gpio";

This gives schema warnings like:

imx28-cfa10037.dtb: pinctrl@80018000: gpio@0:compatible: ['fsl,imx28-gpio', 'fsl,mxs-gpio'] is too long
	from schema $id: http://devicetree.org/schemas/gpio/gpio-mxs.yaml#

"fsl,mxs-gpio" is only used inside pinctrl-mxs, but can be removed if
the compatible check is done against fsl,imx23-gpio and fsl,imx28-gpio.

Introduce is_mxs_gpio() and remove the need for "fsl,mxs-gpio".

Tested on a imx28-evk.

Signed-off-by: Fabio Estevam <festevam@denx.de>
Link: https://lore.kernel.org/r/20230928134321.438547-1-festevam@gmail.com
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

Author: Fabio Estevam

drivers/pinctrl/freescale/pinctrl-mxs.c

@@ -395,14 +395,19 @@ static int mxs_pinctrl_parse_group(struct platform_device *pdev,
 	return 0;
 }
 
+static bool is_mxs_gpio(struct device_node *child)
+{
+	return of_device_is_compatible(child, "fsl,imx23-gpio") ||
+	       of_device_is_compatible(child, "fsl,imx28-gpio");
+}
+
 static int mxs_pinctrl_probe_dt(struct platform_device *pdev,
 				struct mxs_pinctrl_data *d)
 {
 	struct mxs_pinctrl_soc_data *soc = d->soc;
 	struct device_node *np = pdev->dev.of_node;
 	struct device_node *child;
 	struct mxs_function *f;
-	const char *gpio_compat = "fsl,mxs-gpio";
 	const char *fn, *fnull = "";
 	int i = 0, idxf = 0, idxg = 0;
 	int ret;
@@ -417,7 +422,7 @@ static int mxs_pinctrl_probe_dt(struct platform_device *pdev,
 	/* Count total functions and groups */
 	fn = fnull;
 	for_each_child_of_node(np, child) {
-		if (of_device_is_compatible(child, gpio_compat))
+		if (is_mxs_gpio(child))
 			continue;
 		soc->ngroups++;
 		/* Skip pure pinconf node */
@@ -446,7 +451,7 @@ static int mxs_pinctrl_probe_dt(struct platform_device *pdev,
 	fn = fnull;
 	f = &soc->functions[idxf];
 	for_each_child_of_node(np, child) {
-		if (of_device_is_compatible(child, gpio_compat))
+		if (is_mxs_gpio(child))
 			continue;
 		if (of_property_read_u32(child, "reg", &val))
 			continue;
@@ -486,7 +491,7 @@ static int mxs_pinctrl_probe_dt(struct platform_device *pdev,
 	idxf = 0;
 	fn = fnull;
 	for_each_child_of_node(np, child) {
-		if (of_device_is_compatible(child, gpio_compat))
+		if (is_mxs_gpio(child))
 			continue;
 		if (of_property_read_u32(child, "reg", &val)) {
 			ret = mxs_pinctrl_parse_group(pdev, child,