pinctrl: at91-pio4: Add persist state case in config

Adding persist state case to atmel_conf_pin_config_group_set() function.
After adding configuration support for userspace gpiod api, there was an
extra flag PIN_CONFIG_PERSIST_STATE that was not passed in before.

Based on other drivers like TI drivers, added a switch case and return
ENOTSUPP in that case.

Signed-off-by: Ryan Wanner <Ryan.Wanner@microchip.com>
Acked-by: Nicolas Ferre <nicolas.ferre@microchip.com>
Tested-by: Nicolas Ferre <nicolas.ferre@microchip.com>
Link: https://lore.kernel.org/r/20221007151647.98222-3-Ryan.Wanner@microchip.com
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/pinctrl/pinctrl-at91-pio4.c

@@ -775,6 +775,8 @@ static int atmel_conf_pin_config_group_get(struct pinctrl_dev *pctldev,
 			return -EINVAL;
 		arg = (res & ATMEL_PIO_DRVSTR_MASK) >> ATMEL_PIO_DRVSTR_OFFSET;
 		break;
+	case PIN_CONFIG_PERSIST_STATE:
+		return -ENOTSUPP;
 	default:
 		return -ENOTSUPP;
 	}
@@ -883,6 +885,8 @@ static int atmel_conf_pin_config_group_set(struct pinctrl_dev *pctldev,
 				dev_warn(pctldev->dev, "drive strength not updated (incorrect value)\n");
 			}
 			break;
+		case PIN_CONFIG_PERSIST_STATE:
+			return -ENOTSUPP;
 		default:
 			dev_warn(pctldev->dev,
 				 "unsupported configuration parameter: %u\n",