gpio: stm32f7: Fix gpio bank hole management

In case "gpio-ranges" property is not present in device tree,
use default value for gpio_count and gpio_range.
This fixes an issue on stm32 F7 and H7 boards where "pinmux status -a"
command didn't return any pin status due to the fact that both stm32 F7
and H7 board DT doesn't use the gpio-ranges property.

Fixes: dbf928dd2634a6("gpio: stm32f7: Add gpio bank holes management")

Signed-off-by: Patrice Chotard <patrice.chotard@st.com>
diff --git a/drivers/gpio/stm32f7_gpio.c b/drivers/gpio/stm32f7_gpio.c
index f160b4e..dbaa80c 100644
--- a/drivers/gpio/stm32f7_gpio.c
+++ b/drivers/gpio/stm32f7_gpio.c
@@ -171,6 +171,11 @@
 	ret = dev_read_phandle_with_args(dev, "gpio-ranges",
 					 NULL, 3, i, &args);
 
+	if (ret == -ENOENT) {
+		uc_priv->gpio_count = STM32_GPIOS_PER_BANK;
+		priv->gpio_range = GENMASK(STM32_GPIOS_PER_BANK - 1, 0);
+	}
+
 	while (ret != -ENOENT) {
 		priv->gpio_range |= GENMASK(args.args[2] + args.args[0] - 1,
 				    args.args[0]);