panfrost: Implement Z32F_S8 blits

Requires the ability to texture the stencil-only portion, and then
u_blitter kicks in for the rest.

v2: Fix dEQP-GLES31.functional.stencil_texturing.*

Signed-off-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/5858>
3 files changed