panfrost: s/job/batch/

panfrost: s/job/batch/

What we currently call a job is actually a batch containing several jobs
all attached to a rendering operation targeting a specific FBO.

Let's rename structs, functions, variables and fields to reflect this
fact.

Suggested-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
Reviewed-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>