pinctrl: single: fix bias pull up/down handling in pin_config_set

[ Upstream commit 236152dd9b1675a35eee912e79e6c57ca6b6732f ]

In the pin_config_set function, when handling PIN_CONFIG_BIAS_PULL_DOWN or
PIN_CONFIG_BIAS_PULL_UP, the function calls pcs_pinconf_clear_bias()
which writes the register. However, the subsequent operations continue
using the stale 'data' value from before the register write, effectively
causing the bias clear operation to be overwritten and not take effect.

Fix this by reading the 'data' value from the register after calling
pcs_pinconf_clear_bias().

This bug seems to have existed when this code was first merged in commit
9dddb4d ("pinctrl: single: support generic pinconf").

Signed-off-by: Chi Zhang <chizhang@asrmicro.com>
Link: https://lore.kernel.org/20250807062038.13610-1-chizhang@asrmicro.com
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[uli: backport to 4.19]
Signed-off-by: Ulrich Hecht <uli@kernel.org>
Reviewed-by: Pavel Machek <pavel@nabladev.com>

Author: Chi Zhang

drivers/pinctrl/pinctrl-single.c

@@ -562,8 +562,10 @@ static int pcs_pinconf_set(struct pinctrl_dev *pctldev,
 				break;
 			case PIN_CONFIG_BIAS_PULL_DOWN:
 			case PIN_CONFIG_BIAS_PULL_UP:
-				if (arg)
+				if (arg) {
 					pcs_pinconf_clear_bias(pctldev, pin);
+					data = pcs->read(pcs->base + offset);
+				}
 				/* fall through */
 			case PIN_CONFIG_INPUT_SCHMITT_ENABLE:
 				data &= ~func->conf[i].mask;