hwmon: (pwm-fan) Make SENSORS_PWM_FAN depend on OF

This driver won't instantiate if OF is not configured, thus add OF dependency.
Also add COMPILE_TEST to increase build testing coverage.
Signed-off-by: Axel Lin <axel.lin@ingics.com>
Reviewed-by: Jean Delvare <jdelvare@suse.de>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

drivers/hwmon/Kconfig

@@ -1130,7 +1130,7 @@ source drivers/hwmon/pmbus/Kconfig
 
 config SENSORS_PWM_FAN
 	tristate "PWM fan"
-	depends on PWM
+	depends on (PWM && OF) || COMPILE_TEST
 	help
 	  If you say yes here you get support for fans connected to PWM lines.
 	  The driver uses the generic PWM interface, thus it will work on a