nfs41: enable nfs_client only nfs4_async_handle_error
nfs41: enable nfs_client only nfs4_async_handle_error

The session is per struct nfs_client, not per nfs_server. Allow the handler
to be called with no nfs_server which simplifies the nfs4_proc_async_sequence session renewal call and will let it be used by pnfs file layout data servers.

Signed-off-by: Andy Adamson <354e29cfbea2f74d5ce81a3b79d7f0264830cb78@netapp.com>
Signed-off-by: Benny Halevy <23c997c90eb8537635e9392d48e7af1bf1b2ca22@panasas.com>
Signed-off-by: Trond Myklebust <6a1f9db795c9fc44be97d66ab114c53193bd3d13@netapp.com>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs