InCallUI: fix blue call button background on some devices

Fixes reports of this: http://goo.gl/zTgVGQ

PS2: A little bit darker.
Change-Id: I2097018811aa7852604e987b9142a4c3d4aa4a30
Merge branch 'berserk' of github.com:berserkaosp/packages_apps_InCallUI into berserk