arm64: dts: qcom: sdm845-xiaomi-beryllium: Add reserved memory region

Put cont splash memory region under the reserved-memory as
confirmed by the downstream code for both Tianma and EBBG variants.
Signed-off-by: Amit Pundir <amit.pundir@linaro.org>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20230127063355.1775246-1-amit.pundir@linaro.org

arch/arm64/boot/dts/qcom/sdm845-xiaomi-beryllium-common.dtsi

@@ -98,6 +98,12 @@ spss_mem: memory@97f00000 {
 			no-map;
 		};
 
+		/* Cont splash region set up by the bootloader */
+		cont_splash_mem: framebuffer@9d400000 {
+			reg = <0 0x9d400000 0 0x2400000>;
+			no-map;
+		};
+
 		rmtfs_mem: memory@f6301000 {
 			compatible = "qcom,rmtfs-mem";
 			reg = <0 0xf6301000 0 0x200000>;