InCallUI: Workaround for aapt warnings

Change-Id: I1b28aca47f69b5559152e7bc23371a54bd9a47e4
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