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

The ARM architected timer is part of ARM CPU design therefore by
convention it should not be inside the soc node.  This also fixes dtc
warning like:

    arch/arm64/boot/dts/intel/socfpga_agilex.dtsi:410.9-416.5:
        Warning (simple_bus_reg): /soc/timer: missing or empty reg/ranges property

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