SystemUI: ic_brightness_*: drawables get surface color

since google decided not to kill eyes of people with dark qs always but forgot to change the
the color in drawable of Brightnessbar elements. it was white colored.

 before: https://imgur.com/OrW2p7d

 after: https://imgur.com/7DV844t



if you are using gapps( with google overlays) then no need of this else needed

Signed-off-by: Harsh <harsh@project404.us>
Change-Id: If789337a275f46de3615bd0d0158b172ac6dd8c9