tipc: remove tipc_snprintf

tipc_snprintf() was heavily utilized by the old netlink API which no
longer exists (now netlink compat).

In this patch we swap tipc_snprintf() to the identical scnprintf() in
the only remaining occurrence.

Signed-off-by: Richard Alpe <richard.alpe@ericsson.com>
Reviewed-by: Erik Hugne <erik.hugne@ericsson.com>
Reviewed-by: Ying Xue <ying.xue@windriver.com>
Reviewed-by: Jon Maloy <jon.maloy@ericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>