mesa/st: fix color outputs in presence of sample mask output
Commit c5d822da added support for sample mask incorrectly. It became treated as a color output, and messed up the color output indices. Revert the hunk that did that, and add explicit support just like for depth/stencil writes. Signed-off-by:Ilia Mirkin <imirkin@alum.mit.edu> Acked-by:
Marek Olšák <marek.olsak@amd.com>