ARM: dts: msm: Add ocmem node to device tree

On-chip memory(OCMEM) is a high speed memory
device used by various subsystems. Add ocmem
device tree node for msm-samarium.

Signed-off-by: Neeti Desai <neetid@codeaurora.org>
Change-Id: I0cb5ed2a93b867142d3fc2de0a53578427d2e88b