hwmon: (gpd-fan) Fix range check for pwm input

Fixed the maximum value in the PWM input range check, allowing the
input to be set to 255.

Fixes: 0ab88e2 ("hwmon: add GPD devices sensor driver")
Reported-by: Chenx Dust <chenx_dust@outlook.com>
Link: Cryolitia/gpd-fan-driver#18
Co-developed-by: Chenx Dust <chenx_dust@outlook.com>
Signed-off-by: Chenx Dust <chenx_dust@outlook.com>
Signed-off-by: Cryolitia PukNgae <cryolitia@uniontech.com>
Link: https://lore.kernel.org/r/20250919-hwmon-v1-1-2b69c8b9c062@uniontech.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

Author: Cryolitia

drivers/hwmon/gpd-fan.c

@@ -571,7 +571,7 @@ static int gpd_fan_hwmon_write(__always_unused struct device *dev,
 			ret = 0;
 			goto OUT;
 		case hwmon_pwm_input:
-			if (!in_range(val, 0, 255)) {
+			if (!in_range(val, 0, 256)) {
 				ret = -ERANGE;
 				goto OUT;
 			}