pNFS: We want return-on-close to complete when evicting the inode

If the inode is being evicted, it should be safe to run return-on-close,
so we should do it to ensure we don't inadvertently leak layout segments.

Fixes: 1c5bd76d

 ("pNFS: Enable layoutreturn operation for return-on-close")
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>