locks: clean up the lm_change prototype

Now that we use standard list_heads for tracking leases, we can have
lm_change take a pointer to the lease to be modified instead of a
double pointer.

Signed-off-by: Jeff Layton <jlayton@primarydata.com>
Acked-by: Christoph Hellwig <hch@lst.de>

diff --cc fs/locks.c
Simple merge

diff --cc fs/nfsd/nfs4state.c
Simple merge

diff --cc include/linux/fs.h
Simple merge