panfrost: Fix stride calculation for Z32_S8X24/X32_S8X24 formats

Z32_S8X24 variants are actually stored in 2 planes (one per component),
we have to adjust the bytes_per_pixel value accordingly.

Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
Reviewed-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Part-of: <!7653>
81 jobs for !7653 with bifrost-tex in 19 minutes and 32 seconds (queued for 6 seconds)
merge request