arm64: dts: rockchip: assign default rates for core rk3399 clocks

These clocks are all core clocks used by many blocks/peripherals, many
of whose drivers don't set their clock rates at all. Let's assign
reasonable default clock rates for these core clocks, so that these
peripherals get something reasonable by default, and also so that if
child devices want to select a clock rate themselves, their muxes have
some reasonable parent clock rates to branch off of (rather than just
the boot-time defaults).

This helps the eMMC PHY, for one, to get a reasonable ACLK rate.

Signed-off-by: Xing Zheng <zhengxing@rock-chips.com>
Signed-off-by: Brian Norris <briannorris@chromium.org>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>