arm64: dts: rockchip: Drop assigned-clock* from cpu nodes on rk3588

arm64: dts: rockchip: Drop assigned-clock* from cpu nodes on rk3588

The assigned-clocks and assigned-clock-rates properties were moved from
the scmi_clk node onto cpu nodes in commit
87810bda8a84 ("arm64: dts: rockchip: Fix SCMI assigned clocks on rk3588s")

During review of v1 of that patch set, the following comment was made:

  why aren't you using OPP tables to define CPU frequencies.
  Assigned-clocks looks like a temporary hack because you haven't
  done proper OPP tables.

Some time later, proper OPP tables for rk3588 were added in commit
276856db91b4 ("arm64: dts: rockchip: Add OPP data for CPU cores on RK3588")

So this 'temporary hack' is no longer needed.
Dropping it fixes the following dtb validation issues:

  cpu@0: Unevaluated properties are not allowed
    ('assigned-clock-rates', 'assigned-clocks' were unexpected)
  cpu@400: Unevaluated properties are not allowed
    ('assigned-clock-rates', 'assigned-clocks' were unexpected)
  cpu@600: Unevaluated properties are not allowed
    ('assigned-clock-rates', 'assigned-clocks' were unexpected)

Link: https://lore.kernel.org/linux-rockchip/CAL_JsqL_EogoKOQ1xwU75=rJSC4o7yV3Jej4vadtacX2Pt3-hw@mail.gmail.com/
Signed-off-by: Diederik de Haas <didi.debian@cknow.org>
Link: https://lore.kernel.org/r/20250519101909.62754-1-didi.debian@cknow.org
Signed-off-by: Heiko Stuebner <heiko@sntech.de>