intel: workaround VS fixed function issue on Gen9 GT1 parts

intel: workaround VS fixed function issue on Gen9 GT1 parts

The issue is noticeable in the
dEQP-GLES31.functional.geometry_shading.layered.render_with_default_layer_3d
test where a triangle goes missing when we use the maximum number of
URB entries as specified by the documentation.

Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=107505
Reviewed-by: Kristian H. Kristensen <hoegsberg@google.com>
Acked-by: Kenneth Graunke <kenneth@whitecape.org>