defconfig: Enable Power On support for Kona

Enable compilation of msm-poweroff driver for Kona. Also
enable DLOAD_MODE to make Soc goto Download mode when it
resets due to a kernel panic.

Change-Id: I956c8ee96c37c85039477f4c502e9c314582135b
Signed-off-by: Rishabh Bhatnagar <rishabhb@codeaurora.org>