[VTS] BlendMode::Coverage test

Enable BlendMode::Coverage test.
Test pass: BlendMode/GraphicsBlendModeCompositionTest#Premultiplied/0: PASSED (930ms)
BlendMode/GraphicsBlendModeCompositionTest#Premultiplied/1: PASSED (933ms)

BUG: 219737571

Test: atest VtsHalGraphicsComposer3_TargetTest
Change-Id: I5f5bbf371c26933457eec0f3710d47ddadd06cdb
1 file changed