ARM: dts: msm: enable scatter gather etr-ddr mode on 8994v2

Scatter gather option for TMC ETR DDR mode supports the use of a table of
locations of 4K blocks of physical memory. Enable this feature to
facilitate users to increase the trace buffer size as long as DDR memory is
available in the system.

Change-Id: I2d34116bba9663e4a09cc224d8826a208a92d0c3
Signed-off-by: Sarangdhar Joshi <spjoshi@codeaurora.org>