anv: fixup PIPE_CONTROL restriction on gfx8
We're missing a condition that is currently papered over by having ANV_PIPE_HDC_PIPELINE_FLUSH_BIT in the invalidate bits. v2: rework with simplication (Caio) Signed-off-by:Lionel Landwerlin <lionel.g.landwerlin@intel.com> Cc: mesa-stable Reviewed-by:
Caio Oliveira <caio.oliveira@intel.com> Part-of: <mesa/mesa!16905>