Now that NFS client uses the kernel key ring facility to store the NFSv4
id/gid mappings, the defaults for root_maxkeys and root_maxbytes need to be
substantially increased.

These values have been soak tested:

	https://bugzilla.redhat.com/show_bug.cgi?id=1033708#c73Signed-off-by: NSteve Dickson <steved@redhat.com>
Signed-off-by: NDavid Howells <dhowells@redhat.com>
Signed-off-by: NJames Morris <james.l.morris@oracle.com>