arm64: dts: rockchip: Assign RK3399 VDU clock rate

arm64: dts: rockchip: Assign RK3399 VDU clock rate

Before commit 9998943f6dfc ("media: rkvdec: Stop overclocking the
decoder"), the rkvdec driver was forcing the VDU clock rate. After that
commit, we rely on the default clock rate. That rate works OK on many
boards, with the default PLL settings (CPLL is 800MHz, VDU dividers
leave it at 400MHz); but some boards change PLL settings.

Assign the expected default clock rate explicitly, so that the rate is
consistent, regardless of PLL configuration.

This was particularly broken on RK3399 Gru Scarlet systems, where the
rk3399-gru-scarlet.dtsi assigns PLL_CPLL to 1.6 GHz, and so the VDU
clock ends up at 800 MHz (twice the expected rate), and causes video
artifacts and other issues.

Note: I assign the clock rate in the clock controller instead of the
vdec node, because there are multiple nodes that use this clock, and per
the clock.yaml specification:

  Configuring a clock's parent and rate through the device node that
  consumes the clock can be done only for clocks that have a single
  user. Specifying conflicting parent or rate configuration in multiple
  consumer nodes for a shared clock is forbidden.

  Configuration of common clocks, which affect multiple consumer devices
  can be similarly specified in the clock provider node.

Fixes: 9998943f6dfc ("media: rkvdec: Stop overclocking the decoder")
Cc: <stable@vger.kernel.org>
Signed-off-by: Brian Norris <briannorris@chromium.org>
Reviewed-by: Nicolas Dufresne <nicolas.dufresne@collabora.com>
Link: https://lore.kernel.org/r/20220607141535.1.Idafe043ffc94756a69426ec68872db0645c5d6e2@changeid
Signed-off-by: Heiko Stuebner <heiko@sntech.de>