intel: Generate files with newline at end

This generator scripts uses the `write` function that, unlike `print`,
doesn't print a trailing newline. So let's add one to the template.

Reviewed-by: Faith Ekstrand <faith.ekstrand@collabora.com>
Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/35697>

src/intel/genxml/gen_bits_header.py

@@ -129,7 +129,8 @@ ${emit_per_gen_prop_func(field, 'start', False)}
 }
 #endif
 
-#endif /* ${guard} */""")
+#endif /* ${guard} */
+""")
 
 class Gen(object):