arm64: dts: rockchip: kill pcie_clkreqn and pcie_clkreqnb for rk3399

Kill these two pinctrl reference totally from rk3399 as it
never work indeed.

Signed-off-by: Shawn Lin <shawn.lin@rock-chips.com>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>