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

arch/arm64/boot/dts/qcom/sc7180.dtsi

@@ -88,6 +88,7 @@ aop_mem: memory@80800000 {
 		aop_cmd_db_mem: memory@80820000 {
 			reg = <0x0 0x80820000 0x0 0x20000>;
 			compatible = "qcom,cmd-db";
+			no-map;
 		};
 
 		sec_apps_mem: memory@808ff000 {