meta-romulus: Add iio-hwmon-battery config

Romulus has RTC battery monitored by aspeed adc, add the config for
hwmon to create /xyz/openbmc_project/sensors/voltage/vbat dbus object.

Tested: With romulus dts enabled iio-hwmon-battery, verify the above
        vbat dbus object is created and the value is expected.

Change-Id: Ie97003af0db1dc4d966ac34d4ab975dcae7733e7
Signed-off-by: Lei YU <mine260309@gmail.com>
2 files changed