dm: gpio: Fix gpio_get_list_count failing with livetree

of_parse_phandle_with_args (called by dev_read_phandle_with_args) does not
support getting the length of a phandle list by using the index -1.
Instead, use dev_count_phandle_with_args which supports exactly this
use-case.

Fixes: 8558217153 ("gpio: Convert to use APIs which support live DT")

Signed-off-by: Sean Anderson <sean.anderson@seco.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

drivers/gpio/gpio-uclass.c

@@ -1215,9 +1215,9 @@ int gpio_get_list_count(struct udevice *dev, const char *list_name)
 {
 	int ret;
 
-	ret = dev_read_phandle_with_args(dev, list_name, "#gpio-cells", 0, -1,
-					 NULL);
-	if (ret) {
+	ret = dev_count_phandle_with_args(dev, list_name, "#gpio-cells",
+					  -ENOENT);
+	if (ret < 0) {
 		debug("%s: Node '%s', property '%s', GPIO count failed: %d\n",
 		      __func__, dev->name, list_name, ret);
 	}