arm64: dts: qcom: sdm670: add smem region

The shared memory region is used for information about the SoC and
communication with remote processors. Add the smem region for SDM670.

Signed-off-by: Richard Acayan <mailingradian@gmail.com>
Link: https://lore.kernel.org/r/20240524012023.318965-8-mailingradian@gmail.com


Signed-off-by: Bjorn Andersson <andersson@kernel.org>