Making buttons lose brightness when disabled.

Fixing bug where disabled buttons in SUW were not distinguishable from
enabled buttons

Change-Id: I7b334871e10e0093b92522b0fb37e3eda152f9a9
Fixes: 113174594
Test: Manual check of button state
(cherry picked from commit fbb4373b13b0fe52e81a4cd6824c275642fc756a)