radv: move descriptor sets out of cmd_state.

radv: move descriptor sets out of cmd_state.

Instead of storing all the pointers and zeroing them all out,
just store a valid bitmask in the state. This also moves
the CmdBindPipeline path down the cpu usage path for the
multithreading demo as it no longer has to traverse MAX_SETS
to find the active descriptor sets.

Reviewed-by: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl>
Signed-off-by: Dave Airlie <airlied@redhat.com>