NFSv4: Fix second deadlock in nfs4_evict_inode()

commit c3aba897

 upstream.

If the inode is being evicted but has to return a layout first, then
that too can cause a deadlock in the corner case where the server
reboots.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>