radeon/vcn: add common encode part

Add a skeleton pipe video interface and encode ib interface for video encode
on vcn hardware. Add function defines and structures for vcn encode. Update
Makefile.sources and meson.build with newly added files.

Signed-off-by: Boyuan Zhang <boyuan.zhang@amd.com>
Acked-by: Christian König <christian.koenig@amd.com>
5 files changed