arm64: dts: qcom: sdm845-db845c: Mark cont splash memory region as reserved

Adding a reserved memory region for the framebuffer memory
(the splash memory region set up by the bootloader).

It fixes a kernel panic (arm-smmu: Unhandled context fault
at this particular memory region) reported on DB845c running
v5.10.y.

Cc: stable@vger.kernel.org # v5.10+
Reviewed-by: Caleb Connolly <caleb.connolly@linaro.org>
Signed-off-by: Amit Pundir <amit.pundir@linaro.org>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20230726132719.2117369-2-amit.pundir@linaro.orgSigned-off-by: Bjorn Andersson <andersson@kernel.org>

arch/arm64/boot/dts/qcom/sdm845-db845c.dts

@@ -101,6 +101,14 @@ hdmi_con: endpoint {
 		};
 	};
 
+	reserved-memory {
+		/* Cont splash region set up by the bootloader */
+		cont_splash_mem: framebuffer@9d400000 {
+			reg = <0x0 0x9d400000 0x0 0x2400000>;
+			no-map;
+		};
+	};
+
 	lt9611_1v8: lt9611-vdd18-regulator {
 		compatible = "regulator-fixed";
 		regulator-name = "LT9611_1V8";
@@ -513,6 +521,7 @@ &i2c14 {
 };
 
 &mdss {
+	memory-region = <&cont_splash_mem>;
 	status = "okay";
 };