arm64: dts: msm8992: add pstore-ramoops support

With the addition of this ramoops node it enables post mortem
analysis if a debug cable is not attached and/or not available.

All addresses and values were extracted from CAF AOSP marshmallow
DR 1.6.

Signed-off-by: Jeremy McNicoll <jeremymc@redhat.com>
Acked-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Andy Gross <andy.gross@linaro.org>