iris: remove dead code that cannot get hit anymore

As of recent changes, MESA_SHADER_GEOMETRY is handled by the if ladder.

CID: 1643918
Fixes: c33ebf09f5e ("iris: fix handling of GL_*_VERTEX_CONVENTION")
Signed-off-by: Tapani Pälli <tapani.palli@intel.com>
Reviewed-by: Dylan Baker <dylan.c.baker@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/33842>
1 file changed