rockchip: rk3328: Fix bootph prop for vop node

The vop node should not be included in TPL/SPL control FDT, it should
only be included at U-Boot proper pre-reloc phase.

Change to use bootph-some-ram prop to fix this.

Fixes: 6794063d ("ARM: dts: rk3328: Enable VOP for bootph-all")
Signed-off-by: Jonas Karlman <jonas@kwiboo.se>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>