iris: Add fast-clear restriction for 8bpp surfaces

For 8bpp surfaces on TGL, prevent LOD1+ from being fast-cleared. This
will be relevant once ISL starts allowing CCS for 8bpp surfaces with
more than 2 miplevels. I verified the problem behind this restriction
with a modified version of the fbo-clearmipmap piglit test.

Reviewed-by: Sagar Ghuge <sagar.ghuge@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/7085>
1 file changed