ARM: dts: bcm2837-rpi-3-b: Add bcm43438 serial slave

Add BCM43438 (bluetooth) as a slave device of uart0 (pl011/ttyAMA0).
This allows to automatically insert the bcm43438 to the bluetooth
subsystem instead of relying on userspace helpers (hciattach).

Overwrite chosen/stdout-path to use 8250 aux uart as console.
Acked-by: NRob Herring <robh@kernel.org>
Signed-off-by: NLoic Poulain <loic.poulain@gmail.com>
Signed-off-by: NEric Anholt <eric@anholt.net>

arch/arm/boot/dts/bcm2837-rpi-3-b.dts

@@ -29,6 +29,11 @@ &uart0 {
 	pinctrl-names = "default";
 	pinctrl-0 = <&uart0_gpio32 &gpclk2_gpio43>;
 	status = "okay";
+
+	bluetooth {
+		compatible = "brcm,bcm43438-bt";
+		max-speed = <2000000>;
+	};
 };
 
 /* uart1 is mapped to the pin header */