meta-romulus: Add GPIOCHIP in iio-hwmon-battery.conf

phosphor-hwmon requires GPIOCHIP to be set for GPIO gating.
Add this config for Romulus to make it work.

Tested: Verify the rtc voltage is read correctly.

Change-Id: If3cbb99bac5b31a978089d83f3e97488c25d51e4
Signed-off-by: Lei YU <mine260309@gmail.com>
diff --git a/meta-romulus/recipes-phosphor/sensors/phosphor-hwmon%/obmc/hwmon/iio-hwmon-battery.conf b/meta-romulus/recipes-phosphor/sensors/phosphor-hwmon%/obmc/hwmon/iio-hwmon-battery.conf
index c72b3b5..61abf6e 100644
--- a/meta-romulus/recipes-phosphor/sensors/phosphor-hwmon%/obmc/hwmon/iio-hwmon-battery.conf
+++ b/meta-romulus/recipes-phosphor/sensors/phosphor-hwmon%/obmc/hwmon/iio-hwmon-battery.conf
@@ -2,6 +2,7 @@
 GAIN_in1=2.25
 
 # GPIOR3 needs to be pulled high for battery voltage reading
+GPIOCHIP_in1=0
 GPIO_in1=139
 
 # Read it every day so it does not impact battery life