ARM: dts: BCM63xx: Add PMB busses nodes

Add the two BCM63138 PMB busses nodes found on this System-on-a-Chip as
described in their corresponding binding document.
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>

arch/arm/boot/dts/bcm63138.dtsi

@@ -105,6 +105,18 @@ twd_watchdog: watchdog@1e620 {
 			reg = <0x1e620 0x20>;
 			interrupts = <GIC_PPI 14 IRQ_TYPE_LEVEL_HIGH>;
 		};
+
+		pmb0: reset-controller@4800c0 {
+			compatible = "brcm,bcm63138-pmb";
+			reg = <0x4800c0 0x10>;
+			#reset-cells = <2>;
+		};
+
+		pmb1: reset-controller@4800e0 {
+			compatible = "brcm,bcm63138-pmb";
+			reg = <0x4800e0 0x10>;
+			#reset-cells = <2>;
+		};
 	};
 
 	/* Legacy UBUS base */