radeonsi: rewrite si_update_ps_colorbuf0_slot to fix crashes and recursions

radeonsi: rewrite si_update_ps_colorbuf0_slot to fix crashes and recursions

I'm convinced that u_blitter interactions with fbfetch can't be handled
in si_update_ps_colorbuf0_slot alone, so it has to be force-disabled
by si_blitter_begin. Another reason why it has to be disabled for u_blitter
and not ignored is because FBFETCH with MSAA enables sample shading
regardless of context states, and we don't want that for u_blitter.

Also, si_update_ps_colorbuf0_slot now disables FBFETCH explicitly before
its own DCC and CMASK decompression because even though u_blitter can't do
anything (due to blitter_running), si_blitter_end calls it too.

The result is that no recursion can occur thanks to the blitter_running
and suppress_update_ps_colorbuf0_slot flags, and FBFETCH is always
force-disabled before those flags are set, which is the state we want
to be in.

Fixes: bc6d22b9200 ("radeonsi: fix ps_uses_fbfetch value")

Acked-by: Yogesh Mohan Marimuthu <yogesh.mohanmarimuthu@amd.com>
Reviewed-by: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/20318>