defconfig: disable DSI parser for sa6155

DSI parser is used to debug different DSI panel settings, and the
xml files used by DSI parser is not defined in sa6155 project.

Change-Id: I8da34bbbb8077077e33a8c8f64e3695be2b6478e
Signed-off-by: Rahul Sharma <rahsha@codeaurora.org>