panfrost: Rewrite scoreboarding routines

panfrost: Rewrite scoreboarding routines

Rather than manipulating job descriptor headers as fat pointers (slow)
and using fancy manipulation functions for programatically building the
tree in arbitrary orders (slow and complicated) and then having to do a
topological sort at runtime every frame (slow) which requires traversing
said headers in GPU memory (slow!)... we finally know enough about
the hardware to just get things right the first time, or second for
next_job linking. So rip out all that code and replace it with a much
better routine to create, upload, and queue a job all in one (since now
it's the same operation essentially - which is much better for memory
access patterns, by the way) and most everything falls into place
gracefully according to the rules we've set out. Even wallpapering isn't
*so* terrible if you just... move that one little... giant... hack out
of sight... ahem....

panfrost_scoreboard_link_batch is no longer a bottleneck, mostly because
it no longer exists :-)

Signed-off-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/merge_requests/3836>