arm: dts: rockchip: remove upstreamed props for Radxa ROCK 5B

"usb_host1_xhci" and related node were already upstreamed. remove
unnecessary properties from u-boot.dtsi.

Signed-off-by: FUKAUMI Naoki <naoki@radxa.com>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>