Using NV12 layout in dmabuf mode giving mis-aligned
VPP output with the media-driver. Keep the NV12 support
(so that we can file the bug agianst msdk or mediadriver),
but lower the ordering so that BGRA picks as default.

NV12 issue can be reproduced with explicit capfilter:
vidoetestsrc ! msdkvpp ! video/x-raw\(memory:DMABuf\),format=NV12 ! glimagesink