net: ipc_router: Initialize IPC Router security sub-module in core init

Currently IPC Router security sub-module is initialized as part of IPC
Router module initialization. This leads to crash if any of the remote
subsystems start communicating with IPC Router before the IPC Router is
completely initialized.

Initialize the IPC Router security sub-module during core initialization
procedure.

Change-Id: I05991c952c565bb9165eb970775de8709e4eb9b8
Signed-off-by: Atish Kumar Patra <apatra@codeaurora.org>