composer: return pending config changes

Config changes were being dropped because GetActiveConfig
was not returning the pending config when a config was pending, but
always returning the applied config

Bug: 138303350
Test: repeatedly turning device on/off, entering aod
Test: verify that this code return active config during aod scenarios
Test: VtsHalGraphicsComposerV2_{1,2,3}TargetTest
Change-Id: I87a8dc1d58f60a73e4dd1679d145c6292da80a60
2 files changed