nir: check shader type before writing to shaderinfo.tess union

nir: check shader type before writing to shaderinfo.tess union

If the shader is not a tesselation shader, then writing to the tess
member of the shaderinfo union will overwrite other members and crash.

Closes: #2722
Fixes: f1dd81ae104 ("nir: Collect if shader uses cross-invocation or indirect I/O.")
Reviewed-by: Timur Kristóf <timur.kristof@gmail.com>
Reviewed-by: Caio Marcelo de Oliveira Filho <caio.oliveira@intel.com>
Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/4408>