st/mesa: report correct precision information for low/medium/high ints

st/mesa: report correct precision information for low/medium/high ints

When we have native integers, these have full precision. Whether they're
low/medium/high isn't piped through the TGSI yet, but eventually those
might have differing precisions. For now they're just 32-bit ints.

Fixes the following dEQP tests:

  dEQP-GLES3.functional.state_query.shader.precision_vertex_highp_int
  dEQP-GLES3.functional.state_query.shader.precision_fragment_highp_int

which expected highp ints to have full 32-bit precision, not the default
23-bit float precision.

Signed-off-by: Ilia Mirkin <imirkin@alum.mit.edu>
Reviewed-by: Dave Airlie <airlied@redhat.com>