net: ipc_router: Send HELLO message after transport UP

Send HELLO message after transport up notification, instead of
waiting for the remote to send the HELLO message and process it.
This is needed for exports that do not initialize until a hello
message is received.

CRs-Fixed: 2263332
Change-Id: Ib39eb5bc90887e47a75d6726cc84d10a8f5eecf4
Signed-off-by: Arun Kumar Neelakantam <aneela@codeaurora.org>