tipc: replace 0 by NULL for pointers
tipc: replace 0 by NULL for pointers

Fix sparse warning:
net/tipc/link.c:1924:40: warning: Using plain integer as NULL pointer

Signed-off-by: Fabian Frederick <3efd2a027b14fd890cd23a9ef6d1134b4e5ad850@skynet.be>
Acked-by: Ying Xue <c1cbb87de349443b90fa63f6d2cc5403843bc133@windriver.com>
Signed-off-by: David S. Miller <fe08d3c717adf2ae63592e4c9aec6e3e404d8e3e@davemloft.net>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs