ARM: dts: NSP: Fix MX65 MDIO mux warnings

The naming of this node is based upon that of the initial EA9500 dts[1].
However this does not conform with the mdio-mux format, yielding the
following message when running dtbs_check:
mdio-mii-mux: $nodename:0: 'mdio-mii-mux' does not match '^mdio-mux[\\-@]?'

Secondly, this node should be moved to within the axi node and given the
appropriate unit address. This also requires exposing the axi node via a
label in bcm-nsp.dtsi. This fixes the following warning:
Warning (unit_address_vs_reg): /mdio-mii-mux: node has a reg or ranges property, but no unit name

[1]https://patchwork.ozlabs.org/project/linux-imx/patch/20180618174159.86150-1-npcomplete13@gmail.com/#1941353Signed-off-by: Matthew Hagan <mnhagan88@gmail.com>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>

arch/arm/boot/dts/bcm-nsp.dtsi

@@ -166,7 +166,7 @@ periph_clk: periph_clk {
 		};
 	};
 
-	axi@18000000 {
+	axi: axi@18000000 {
 		compatible = "simple-bus";
 		ranges = <0x00000000 0x18000000 0x0011c40c>;
 		#address-cells = <1>;

arch/arm/boot/dts/bcm958625-meraki-alamo.dtsi

@@ -70,10 +70,12 @@ led-5 {
 			gpios = <&gpioa 31 GPIO_ACTIVE_HIGH>;
 		};
 	};
+};
 
-	mdio-mii-mux {
+&axi {
+	mdio-mux@3f1c0 {
 		compatible = "mdio-mux-mmioreg", "mdio-mux";
-		reg = <0x1803f1c0 0x4>;
+		reg = <0x3f1c0 0x4>;
 		mux-mask = <0x2000>;
 		mdio-parent-bus = <&mdio_ext>;
 		#address-cells = <1>;