pinctrl: at91-pio4: fix pull-up/down logic

The default configuration of a pin is often with a value in the
pull-up/down field at chip reset. So, even if the internal logic of the
controller prevents writing a configuration with pull-up and pull-down at
the same time, we must ensure explicitly this condition before writing the
register.

This was leading to a pull-down condition not taken into account for
instance.

Signed-off-by: Ludovic Desroches <ludovic.desroches@atmel.com>
Fixes: 7761808 ("pinctrl: introduce driver for Atmel PIO4 controller")
Cc: stable@vger.kernel.org #v4.4 and later
Acked-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/pinctrl/pinctrl-at91-pio4.c

@@ -722,9 +722,11 @@ static int atmel_conf_pin_config_group_set(struct pinctrl_dev *pctldev,
 			break;
 		case PIN_CONFIG_BIAS_PULL_UP:
 			conf |= ATMEL_PIO_PUEN_MASK;
+			conf &= (~ATMEL_PIO_PDEN_MASK);
 			break;
 		case PIN_CONFIG_BIAS_PULL_DOWN:
 			conf |= ATMEL_PIO_PDEN_MASK;
+			conf &= (~ATMEL_PIO_PUEN_MASK);
 			break;
 		case PIN_CONFIG_DRIVE_OPEN_DRAIN:
 			if (arg == 0)