arm64: dts: qcom: msm8916: Probe the APCS mailbox driver

The APCS block was exposed until now as a syscon, but now we have a
proper driver for this block. Add the compatible string of the new
driver to probe and register the mailbox functionality.
Signed-off-by: Georgi Djakov <georgi.djakov@linaro.org>
Signed-off-by: Andy Gross <andy.gross@linaro.org>

arch/arm64/boot/dts/qcom/msm8916.dtsi

@@ -332,9 +332,10 @@ a53pll: clock@b016000 {
 			#clock-cells = <0>;
 		};
 
-		apcs: syscon@b011000 {
-			compatible = "syscon";
-			reg = <0x0b011000 0x1000>;
+		apcs: mailbox@b011000 {
+			compatible = "qcom,msm8916-apcs-kpss-global", "syscon";
+			reg = <0xb011000 0x1000>;
+			#mbox-cells = <1>;
 		};
 
 		blsp1_uart2: serial@78b0000 {