ARM: dts: msm: enable the etm registers save-restore on MSM8953

Enable the ETM save-restore logic that is used to context save of
CPU-ETM registers across the power collapse.

Change-Id: Ief20ce33741f514ec99b79aefb36cf9c7af842d0
Signed-off-by: Charan Teja Reddy <charante@codeaurora.org>