uclient: fix snaprealm update in add_update_cap
uclient: fix snaprealm update in add_update_cap

Make conditional consistent with the in->snaprealm clearing in the
cap removal path.

This was throwing a bad assertion during mds restart.

ajnelson/ceph,ajnelson/ceph,ajnelson/ceph,ajnelson/ceph,ajnelson/ceph,ajnelson/ceph