8974:slim: Use direct access registers instead of RX message queues

BAM pipe for receiving control information is not assigned to apps
for slimbus on 8974. Use register access instead.

Change-Id: Ieac5aa54555e206f91606c5e20c0f6eefb6e7c36
Signed-off-by: Sagar Dharia <sdharia@codeaurora.org>
diff --git a/arch/arm/boot/dts/msm8974.dtsi b/arch/arm/boot/dts/msm8974.dtsi
index 70c85c6..f144421 100644
--- a/arch/arm/boot/dts/msm8974.dtsi
+++ b/arch/arm/boot/dts/msm8974.dtsi
@@ -216,6 +216,7 @@
 		interrupts = <0 163 0 0 164 0>;
 		interrupt-names = "slimbus_irq", "slimbus_bam_irq";
 		qcom,min-clk-gear = <10>;
+		qcom,rxreg-access;
 	};
 
 	spmi_bus: qcom,spmi@fc4c0000 {