net: ipc_router: Reference count routing table entries and remote ports

Everytime a routing table entry or a remote port is searched and then
accessed, a global lock is used to protect the access for its entire
duration.

Define a reference element in the concerned structure. Get a reference
to the entry everytime it is searched and accessed. Put the reference back
once the access is complete. Release the data structure when the reference
count is zero.

Change-Id: I95312e4903167dda50c83ecf2e2a409b9dcbf6bd
Signed-off-by: Karthikeyan Ramasubramanian <kramasub@codeaurora.org>