ARM: dts: msm: add dt entry for memory dump table for 8939

Add device tree entry for memory dump imem base and size info that
can be used by the memory dump v2 driver to register dump clients.

Change-Id: Ife3e4f127db75e77514f03d7f59f645123c564f3
Signed-off-by: Xiaogang Cui <xiaogang@codeaurora.org>