arm64: dts: intel: socfpga_agilex: move clocks out of soc node

The clocks are usually not part of the SoC but provided on the board
(external oscillators).  Moving them out of soc node fixes dtc warning:

    arch/arm64/boot/dts/intel/socfpga_agilex.dtsi:111.10-137.5:
        Warning (simple_bus_reg): /soc/clocks: missing or empty reg/ranges property

Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Signed-off-by: Dinh Nguyen <dinguyen@kernel.org>