arm64: dts: rockchip: fix the pcie refclock oscillator on Rock 5 ITX

The Rock 5 ITX uses two PCIe controllers to drive both a M.2 slot and its
SATA controller with 2 lanes each. The supply for the refclk oscillator is
the same that supplies the M.2 slot, but the SATA controller port is
supplied by a different rail.

This leads to the effect that if the PCIe30x4 controller for the M.2
probes first, everything works normally. But if the PCIe30x2 controller
that is connected to the SATA controller probes first, it will hang on
the first DBI read as nothing will have enabled the refclock before.

Fix this by describing the clock generator with its supplies so that
both controllers can reference it as needed.

Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Link: https://lore.kernel.org/r/20240906082511.2963890-6-heiko@sntech.de