ARM: dts: msm: add remote debugger driver dt node on 8974

The  Remote Debugger Driver allows a debugger running on a host
PC to communicate with a remote stub running on peripheral
subsystems. Add device tree node for this driver on MSM8974.

Change-Id: I7aaef963eaed54cd23c7e877050f3a10bf9249ba
Acked-by: Vivek Iyer <viyer@qti.qualcomm.com>
Acked-by: Mahesh Rohera <mrohera@qti.qualcomm.com>
Acked-by: Jay Jayanna <jjayanna@qti.qualcomm.com>
Signed-off-by: Aparna Das <adas@codeaurora.org>