glsl: prohibit lowp, mediump precision on atomic_uint
glsl: prohibit lowp, mediump precision on atomic_uint

Fixes following dEQP tests:

   dEQP-GLES31.functional.debug.negative_coverage.callbacks.atomic_counter.atomic_precision
   dEQP-GLES31.functional.debug.negative_coverage.get_error.atomic_counter.atomic_precision
   dEQP-GLES31.functional.debug.negative_coverage.log.atomic_counter.atomic_precision

Signed-off-by: Tapani Pälli <cdcb67a5e49297de94340ca09f25994bd5e7f762@intel.com>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=98131
Reviewed-by: Kenneth Graunke <bd2562f754ec92342f93f61c25d731e290a2ffa8@whitecape.org>

metora/MesaGLSLCompiler,metora/MesaGLSLCompiler,metora/MesaGLSLCompiler