tipc: remove size variable from publ_list struct

The size variable is introduced in publ_list struct to help us exactly
calculate SKB buffer sizes needed by publications when all publications
in name table are delivered in bulk in named_distribute(). But if
publication SKB buffer size is assumed to MTU, the size variable in
publ_list struct can be completely eliminated at the cost of wasting
a bit memory space for last SKB.

Signed-off-by: Ying Xue <ying.xue@windriver.com>
Signed-off-by: Tero Aho <tero.aho@coriant.com>
Reviewed-by: Erik Hugne <erik.hugne@ericsson.com>
Reviewed-by: Jon Maloy <jon.maloy@ericsson.com>
Tested-by: Erik Hugne <erik.hugne@ericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>