arm64: dts: marvell: Fix pca954x i2c-mux node names

"make dtbs_check":

    arch/arm64/boot/dts/marvell/armada-8040-mcbin.dtb: i2c-switch@70: $nodename:0: 'i2c-switch@70' does not match '^(i2c-?)?mux'
	    From schema: Documentation/devicetree/bindings/i2c/i2c-mux-pca954x.yaml
    arch/arm64/boot/dts/marvell/armada-8040-mcbin.dtb: i2c-switch@70: Unevaluated properties are not allowed ('#address-cells', '#size-cells', 'i2c@0', 'i2c@1', 'i2c@2' were unexpected)
	    From schema: Documentation/devicetree/bindings/i2c/i2c-mux-pca954x.yaml
    ...

Fix this by renaming PCA954x nodes to "i2c-mux", to match the I2C bus
multiplexer/switch DT bindings and the Generic Names Recommendation in
the Devicetree Specification.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Gregory CLEMENT <gregory.clement@bootlin.com>