Changes

Pass xua_msg down to xua_as_transmit_msg

This finally allows having access to msg values such as OPC and SLS at
the point in code where decision is taken to route the message to one
ASP inside the AS.
This will be needed to properly implemented ASP loadsharing within an
AS.

Change-Id: I70e5d33c7537dc0b72b5abced876e69018cc0829