RTP_Emulation: Several fixes and improvements for IuUP streams

* Immediate tx of IuUP (N)ACK control packets. Without this, INIT ACK
is delayed until the TX side of the RTP endpoint is enabled.

* Allow and handle IuUP control messages even if g_rx_enabled is false.

* Properly validate user data payload if IuUP is in use.

Change-Id: Id4f8b02a8123bb30b659c40148c8ab4c7c2078a1
1 file changed