uboot-phytec

rockchip: Clean up CPU selection

In preparation for RK3368 and RK3399, which need to select ARM64, don't
select CPU_V7 at the ARCH_ROCKCHIP level but at the SoC level instead.

Cc: Kever Yang <kever.yang@rock-chips.com>
Signed-off-by: Andreas Färber <afaerber@suse.de>
Acked-by: Simon Glass <sjg@chromium.org>