qrtr: Fix broadcast packet format

The remote processor IPCRTR drivers expect the format for broadcast
control messages to have the node id set to the actual processor id
and the port id to be set to the broadcast identifier.

Change the broadcast enqueue function to this format for remote
processors. Keep the local broadcast format the same.

Change-Id: I7bb7e03d81ec86ba88c68f944c0f197485a6673c
Signed-off-by: Chris Lew <clew@codeaurora.org>