ANDROID: GKI: power_supply: Add SCALE_MODE_EN power-supply property

Add POWER_SUPPLY_PROP_SCALE_MODE_EN property to indicate
the status of filtered voltage based SOC scaling.

Signed-off-by: Sahil Chandna <chandna@codeaurora.org>
(cherry picked from commit e9ab4eff9e48f99d318dd2bd3173a3a8cd0afd8e)
Signed-off-by: Mark Salyzyn <salyzyn@google.com>
Bug: 150789066
Change-Id: I2d110348eb5ecc85847879b9bc783ddc39e934b7