isl: Fix the aux-map encoding for D24_UNORM_X8

Bspec: 53911 now defines the encoding for this format.

Cc: mesa-stable
Reviewed-by: Sagar Ghuge <sagar.ghuge@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/7198>
1 file changed