defconfig: 8974: enable remote debugger driver

The Remote Debugger Driver allows a debugger running on a host
PC to communicate with a remote stub running on peripheral
subsystems. Enable this driver on MSM8974.

Change-Id: I97c0920d4e178fda492b8cd147044da14ff3e191
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>