Change the conditions of layer as translucent

Only the  mSidebandStream  and mActiveBuffer are both null,the layer
is consider as translucent.Or else ,it will cause Composition::sideband
layer can not call into clear ClientTarget when SurfaceFlinger
doComposeSurfaces

Issue: 234427
Test: Live Channel
Change-Id: I19aeb7ac838baefe4b9b9417f87dd8a7d9b131b0
1 file changed