[U-Boot] rockchip: use UUID for root partitions

[Philipp Tomsich]

> We use to use /dev/mmcbl0p7 as root partition, and pass it
> to kernel by cmdline, but the mmc number in kernel in not
> fixed, we need to change the bootargs to adapt it from time
> to time.
> We can use the UUID to fix it, the ID is from:
> https://www.freedesktop.org/wiki/Specifications/DiscoverablePartitionsSpec/
> ARM 32bit: 69dad710-2ce4-4e3c-b16c-21a1d49abed3
> ARM 64bit: b921b045-1df0-41c3-af44-4c6f280d3fae
> 
> Signed-off-by: Kever Yang <kever.yang at rock-chips.com>
> ---
> 
>  include/configs/rockchip-common.h | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
> 

Acked-by: Philipp Tomsich <philipp.tomsich at theobroma-systems.com>