radv/gfx9: use a bigger hammer to flush cb/db caches.

amdvlk is probably more subtle than this but it never uses
the inv cb/db variants, we fail some CTS tests without this.

Fixes:
dEQP-VK.renderpass.dedicated_allocation.formats.d32_sfloat_s8_uint.input*.

Fixes: c2fbeb7c (radv: add GFX9 cache flushing support.)
Reviewed-by: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl> (for now :-)
Signed-off-by: Dave Airlie <airlied@redhat.com>
(cherry picked from commit 868377ab)