nfsd: fix legacy client tracking initialization

Get rid of the nfsd4_legacy_tracking_ops->init() call in
check_for_legacy_methods(). That will be handled in the caller
(nfsd4_client_tracking_init()). Otherwise, we'll wind up calling
nfsd4_legacy_tracking_ops->init() twice, and the second time we'll
trigger the BUG_ON() in nfsd4_init_recdir().

Fixes: 74fd48739d04 ("nfsd: new Kconfig option for legacy client tracking")
Reported-by: Jur van der Burg <jur@avtware.com>
Link: https://bugzilla.kernel.org/show_bug.cgi?id=219580
Signed-off-by: Scott Mayhew <smayhew@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Tested-by: Salvatore Bonaccorso <carnil@debian.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>