arm64: dts: qcom: sc7180: Add "no-map" to cmd_db reserved area

The example in the bindings and all the current users (except sc7180)
have "no-map".  I'm pretty sure we need it on sc7180 too.  Add it.

Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Fixes: e0abc5eb ("arm64: dts: qcom: sc7180: Add cmd_db reserved area")
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Link: https://lore.kernel.org/r/20200424085121.1.I9d1e84d30f488cdb5a957f582abaecd2c0b24d70@changeid


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