tipc: Rename "multicast-link" to "broadcast-link"

Make a cosmetic change to the name displayed for the broadcast link,
to better reflect its true nature. Since TIPC utilizes this link to
distribute name table information, in addition to multicast messages
sent by user applications, the prior name "multicast-link" is
no longer appropriate.

Signed-off-by: Allan Stephens <allan.stephens@windriver.com>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>