arm64: dts: sdm845: Add zap shader region for GPU

Some Adreno GPU targets require a special zap shader to bring the GPU
out of secure mode. Define a region to allocate and store the zap
shader.
Signed-off-by: Jordan Crouse <jcrouse@codeaurora.org>
[bjorn: Rebase ontop of recent reserved-memory patch]
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Andy Gross <agross@kernel.org>

arch/arm64/boot/dts/qcom/sdm845.dtsi

@@ -2124,6 +2124,10 @@ gpu@5000000 {
 
 			qcom,gmu = <&gmu>;
 
+			zap-shader {
+				memory-region = <&gpu_mem>;
+			};
+
 			gpu_opp_table: opp-table {
 				compatible = "operating-points-v2";