clk: rk3399: Set empty for TCPHY assigned-clocks

clk: rk3399: Set empty for TCPHY assigned-clocks

Due to v5.7-rc1 sync the SD controller nodes in rk3399.dtsi
have SCLK_UPHY0_TCPDCORE, SCLK_UPHY1_TCPDCORE assigned-clocks
which are usually required for Linux and don't require to
handle them in U-Boot.

  assigned-clocks = <&cru SCLK_UPHY0_TCPDCORE>;
  assigned-clocks = <&cru SCLK_UPHY1_TCPDCORE>;

So, mark them as empty in clock otherwise device probe on
those typec phy driver would fail.

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