gpio: omap: handle pin config bias flags

Modify omap_gpio_set_config() to handle pin config bias flags by calling
gpiochip_generic_config().

The pin group for the gpio line must have the corresponding pinconf
properties:

PIN_CONFIG_BIAS_PULL_UP requires "pinctrl-single,bias-pullup"
PIN_CONFIG_BIAS_PULL_DOWN requires "pinctrl-single,bias-pulldown"

This is necessary for pcs_pinconf_set() to find the requested bias
parameter in the PIN_MAP_TYPE_CONFIGS_GROUP pinctrl map.
Signed-off-by: Drew Fustini <drew@beagleboard.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Grygorii Strashko <grygorii.strashko@ti.com>
Acked-by: Tony Lindgren <tony@atomide.com>
Link: https://lore.kernel.org/r/20200715213738.1640030-1-drew@beagleboard.org
Link: https://lore.kernel.org/r/20200717194043.1774643-1-drew@beagleboard.org

drivers/gpio/gpio-omap.c

@@ -897,12 +897,18 @@ static int omap_gpio_set_config(struct gpio_chip *chip, unsigned offset,
 				unsigned long config)
 {
 	u32 debounce;
+	int ret = -ENOTSUPP;
+
+	if ((pinconf_to_config_param(config) == PIN_CONFIG_BIAS_DISABLE) ||
+	    (pinconf_to_config_param(config) == PIN_CONFIG_BIAS_PULL_UP) ||
+	    (pinconf_to_config_param(config) == PIN_CONFIG_BIAS_PULL_DOWN)) {
+		ret = gpiochip_generic_config(chip, offset, config);
+	} else if (pinconf_to_config_param(config) == PIN_CONFIG_INPUT_DEBOUNCE) {
+		debounce = pinconf_to_config_argument(config);
+		ret = omap_gpio_debounce(chip, offset, debounce);
+	}
 
-	if (pinconf_to_config_param(config) != PIN_CONFIG_INPUT_DEBOUNCE)
-		return -ENOTSUPP;
-
-	debounce = pinconf_to_config_argument(config);
-	return omap_gpio_debounce(chip, offset, debounce);
+	return ret;
 }
 
 static void omap_gpio_set(struct gpio_chip *chip, unsigned offset, int value)