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>
diff --git a/meta-openbmc-machines/meta-openpower/meta-ibm/meta-romulus/recipes-phosphor/sensors/phosphor-hwmon%/obmc/hwmon/ahb/apb/pwm-tacho-controller@1e786000.conf b/meta-openbmc-machines/meta-openpower/meta-ibm/meta-romulus/recipes-phosphor/sensors/phosphor-hwmon%/obmc/hwmon/ahb/apb/pwm-tacho-controller@1e786000.conf
index 6f90415..374115c 100644
--- a/meta-openbmc-machines/meta-openpower/meta-ibm/meta-romulus/recipes-phosphor/sensors/phosphor-hwmon%/obmc/hwmon/ahb/apb/pwm-tacho-controller@1e786000.conf
+++ b/meta-openbmc-machines/meta-openpower/meta-ibm/meta-romulus/recipes-phosphor/sensors/phosphor-hwmon%/obmc/hwmon/ahb/apb/pwm-tacho-controller@1e786000.conf
@@ -2,3 +2,7 @@
 LABEL_fan9 = "fan0"
 LABEL_fan11 = "fan1"
 LABEL_fan13 = "fan2"
+
+PWM_TARGET_fan9 = "1"
+PWM_TARGET_fan11 = "2"
+PWM_TARGET_fan13 = "1"