hwmon: (pwm-fan) Declare pwm_fan_of_get_cooling_data static

Address the following sparse warnings.

drivers/hwmon/pwm-fan.c:176:5: warning:
	symbol 'pwm_fan_of_get_cooling_data' was not declared. Should it be static?
drivers/hwmon/pwm-fan.c:176:5: warning:
	no previous prototype for 'pwm_fan_of_get_cooling_data'

pwm_fan_of_get_cooling_data is only used in the pwm-fan driver and thus should
be declared static.

Cc: Lukasz Majewski <l.majewski@samsung.com>
Acked-by: Lukasz Majewski <l.majewski@samsung.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

drivers/hwmon/pwm-fan.c

@@ -173,7 +173,8 @@ static const struct thermal_cooling_device_ops pwm_fan_cooling_ops = {
 	.set_cur_state = pwm_fan_set_cur_state,
 };
 
-int pwm_fan_of_get_cooling_data(struct device *dev, struct pwm_fan_ctx *ctx)
+static int pwm_fan_of_get_cooling_data(struct device *dev,
+				       struct pwm_fan_ctx *ctx)
 {
 	struct device_node *np = dev->of_node;
 	int num, i, ret;