C2VdaBqBlockPool: reply error at fetchGraphicBlock() if configureProducer() fails

configureProducer() doesn't return any status. When this method fails,
the component should stop working immediately. In this CL,
C2VdaBqBlockPool replies error at fetchGraphicBlock(), which is the
main method called by the component, if any error occurs at the
previous configureProducer().

Bug: 162902320
Test: android.media.cts.MediaCodecPlayerTest#testPlaybackSwitchViews
Change-Id: I4a9537b7657fef604ba2e020bcaeb0398ae2a5d0