anv: fix fence underlying primitive checks

anv: fix fence underlying primitive checks

We appear to have got lucky that the only type of temporary fence
payload we could have was a syncobj and that would only happen when
the type of the permanent payload was also a syncobj.

This code was broken if that assumption changed and it did in commit
f9a3d9738b12.

Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Cc: <mesa-stable@lists.freedesktop.org>
Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>
Reviewed-by: Ivan Briano <ivan.briano@intel.com>