r600/sfn: Don't tag mem-ring and stream instructions as exports

r600/sfn: Don't tag mem-ring and stream instructions as exports

Export instructions allow burst writes, so it makes send to try
to allocate consecutive registers, but for ring writes we don't
schedule the outputs correctly to exploit this, so for now
don't mark these instructions as export to let the RA restart
picking colors.

When the scheduler starts to emit the ring writes in the right order
to allow for bust writes we might revisit this.

This fixes
  spec@glsl-1.50@execution@variable-indexing@gs-output-array-vec4-index-wr

Fixes: 79ca456b4837b3bc21cf9ef3c03c505c4b4909f6
   r600/sfn: rewrite NIR backend

Related: https://gitlab.freedesktop.org/mesa/mesa/-/issues/6975

Signed-off-by: Gert Wollny <gert.wollny@collabora.com>
Reviewed-by: Filip Gawin <filip@gawin.net>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/18212>