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>