meta-romulus: Add pwm target for fan sensor

This tells phosphor-hwmon to create FanPwm interface for the fan
sensors.

Tested: Verified it is able to set Target to change the fan pwm.

Change-Id: I79c4cb8fe00812659a2c536d9d2e328b5438e0c6
Signed-off-by: Lei YU <mine260309@gmail.com>
1 file changed