ARM: dts: msm: add cti save entry to cpu cti dt nodes for 8994

Add entry to CoreSight cpu CTI device tree nodes to enable saving
and restoring some CTI registres on L2 SCU rail power off since these
cpu CTIs lose their states when L2 SCU is powered down.

Change-Id: I88bcf81e5cbba6150e3c1ac6427f84882946ab31
Signed-off-by: Aparna Das <adas@codeaurora.org>