locks: fix a memory leak bug in __break_lease()

In __break_lease(), the file lock 'new_fl' is allocated in lease_alloc().
However, it is not deallocated in the following execution if
smp_load_acquire() fails, leading to a memory leak bug. To fix this issue,
free 'new_fl' before returning the error.

Signed-off-by: Wenwen Wang <wenwen@cs.uga.edu>
Signed-off-by: Jeff Layton <jlayton@kernel.org>