composer: Add SetColorMode() support in dummy display

When power state change is in progress, real display is busy and dummy
display is active. Fake color mode setting on dummy display instead of
invoking HWCDisplay::SetColorMode() which is invalid on real display.

Change-Id: I8a8dcf1437f0f1dc0cb6bf2112c90ad4cfa0300d
CRs-Fixed: 2576168
2 files changed