arm64: dts: rk356x-u-boot: Drop combphy1 assigned-clocks/rates

combphy1 is failing to probe due to unhandled assigned-clocks and
assigned-clocks-rates.

=> usb start
starting USB...
Bus usb@fd000000: Failed to get PHY1 for usb@fd000000
Port not available.
Bus usb@fd800000: USB EHCI 1.00

There is no real requirement for them in U-Boot to handle, hence
mark them as deleted-properties for the  probe to success

Signed-off-by: Jagan Teki <jagan@edgeble.ai>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>