radeonsi: isolate real framebuffer changes from the decompression passes (v3)

radeonsi: isolate real framebuffer changes from the decompression passes (v3)

When a stencil buffer is part of the framebuffer state, it is
decompressed but because it's bindless, all draw calls set
stencil_dirty_level_mask to 1.

v2: Marek - set the flags outside the loop
          - also clear and set framebuffer.do_update_surf_dirtiness there
          - do it in the DB->CB copy path too
v3: Marek - save and restore the do_update_surf_dirtiness flag

Signed-off-by: Marek Olšák <marek.olsak@amd.com>
Reviewed-by: Nicolai Hähnle <nicolai.haehnle@amd.com>