panfrost: Add a bit more info about some tiler fields

panfrost: Add a bit more info about some tiler fields

Has been observed that after the job chain has completed, those fields
become populated.

tiler_heap_next_start contains an address inside the tiler heap, a bit
before the value that the GPU writes to tiler_heap_free.

used_hierarchy_mask contains a hex value that corresponds to values
observed as hierarchy masks.

Signed-off-by: Tomeu Vizoso <tomeu.vizoso@collabora.com>
Reviewed-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/4832>