NFS: make nfs_match_client killable

    Actually we don't do anything with return value from
    nfs_wait_client_init_complete in nfs_match_client, as a
    consequence if we get a fatal signal and client is not
    fully initialised, we'll loop to "again" label

    This has been proven to cause soft lockups on some scenarios
    (no-carrier but configured network interfaces)

Signed-off-by: Roberto Bergantinos Corpas <rbergant@redhat.com>
Reviewed-by: Benjamin Coddington <bcodding@redhat.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>