net: tipc: kerneldoc fixes

Fix parameter description of tipc_link_bc_create()

Reported-by: Hulk Robot <hulkci@huawei.com>
Fixes: 16ad3f40

 ("tipc: introduce variable window congestion control")
Signed-off-by: Lu Wei <luwei32@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>