Revert "nfsd: separate nfsd_last_thread() from nfsd_put()"

Revert "nfsd: separate nfsd_last_thread() from nfsd_put()"

This reverts commit 03d68ffc48b94cc1e15bbf3b4f16f1e1e4fa286a which is
commit 9f28a971ee9fdf1bf8ce8c88b103f483be610277 upstream.

It is reported to cause issues, so revert it.

Reported-by: email200202 <email200202@yahoo.com>
Link: https://lore.kernel.org/r/e341cb408b5663d8c91b8fa57b41bb984be43448.camel@kernel.org
Cc: NeilBrown <neilb@suse.de>
Cc: Jeff Layton <jlayton@kernel.org>
Cc: Chuck Lever <chuck.lever@oracle.com>
Cc: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>