arm64: dts: microchip: sparx5_pcb134: move non-MMIO nodes out of axi

simple-bus nodes, so the "axi" node, should not have non-MMIO children
as pointed out by simple-bus schema dtbs_check:

  sparx5_pcb134.dtb: axi@600000000: i2c-mux-0: {'compatible': ... should not be valid under {'type': 'object'}
    from schema $id: http://devicetree.org/schemas/simple-bus.yaml#Reported-by: Rob Herring <robh@kernel.org>
Closes: https://lore.kernel.org/all/CAL_Jsq+PtL3HTKkA_gwTjb_i1mFZ+wW+qwin34HMYmwW7oNDFw@mail.gmail.com/Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>