tipc: Remove support for TIPC mode change callback

Eliminates support for the callback routine invoked when TIPC
changes its mode of operation from inactive to standalone or from
standalone to networked. This callback was part of TIPC's obsolete
native API and is not used by TIPC internally.

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>