defconfig: arm64: Enable msm poweroff driver for smd855

Enable msm poweroff driver to support device
shutdown and reset modes. Also enable download
mode support when device is crashed for sdm855.

Change-Id: I4b05cfbde1e0cf196b8aabc23d12b8dbdb5fea5c
Signed-off-by: Prasad Sodagudi <psodagud@codeaurora.org>