panfrost: Move special Z32_S8X24 case out of panfrost_setup_layout()

panfrost: Move special Z32_S8X24 case out of panfrost_setup_layout()

We are about to move the panfrost_setup_layout() logic out of the
gallium driver, and the Z32_S8X24 split is not mandatory (some GPU
support this format natively). Let's move this special case out of
panfrost_setup_layout() and patch the format of the first plane
instead.

Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
Reviewed-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/10033>