Add functions to initialize tile slice structure and make tile slice:
- vaapi_encode_init_tile_slice_structure
- vaapi_encode_make_tile_slice
Tile slice is not allowed to cross the boundary of a tile due to
the constraints of media-driver. Currently adding support for one
slice per tile.
N x N tile encoding is supposed to be supported with the the
capability of ARBITRARY_MACROBLOCKS slice structures.
N X 1 tile encoding should also work in ARBITRARY_ROWS slice
structure.
Signed-off-by: Linjie Fu <linjie.justin.fu@gmail.com>