hwc: Do not use copybit if planeAplha and downscaling invloved

C2D can not handle plane alpha with downscaling properly, so
do not use copybit for such layers.

Conflicts:
        libhwcomposer/hwc_copybit.cpp

CRs-Fixed: 617718
Change-Id: I879bec6365a09bcaa803ed1a765f1e4dd9999474
hwc_copybit: wait on fb target acquire fence before composition

Copybit need to wait for the FrameBufferTarget acquired fence fd
before drawing on it as it uses FB target buffer for composition.

CRs-Fixed: 623231
Change-Id: I8e79871d307aa74ad608b0e077e3c7605a8b0de8