arm64: dts: rockchip: Use only supported PCIe link speed on rk3399

The max link speed supported by the rk3399 is already set in the
rk3399.dtsi file so don't set unsupported link speeds in device
specific DTs. This is the same fix as 642fb279.

Signed-off-by: Peter Robinson <pbrobinson@gmail.com>
Link: https://lore.kernel.org/r/20210413141709.845592-1-pbrobinson@gmail.com


Signed-off-by: Heiko Stuebner <heiko@sntech.de>