MIPS: mscc: jaguar2: Fix pca9545 i2c-mux node names

"make dtbs_check":

    arch/mips/boot/dts/mscc/jaguar2_pcb110.dtb: pca9545@70: $nodename:0: 'pca9545@70' does not match '^(i2c-?)?mux'
	    From schema: Documentation/devicetree/bindings/i2c/i2c-mux-pca954x.yaml
    arch/mips/boot/dts/mscc/jaguar2_pcb110.dtb: pca9545@70: Unevaluated properties are not allowed ('#address-cells', '#size-cells', 'i2c@0', 'i2c@1', 'i2c@2', 'i2c@3' were unexpected)
	    From schema: Documentation/devicetree/bindings/i2c/i2c-mux-pca954x.yaml
    ...

Fix this by renaming PCA9545 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>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>