Add support for rkrng variant, used by e.g. RK3528 and RK3576.
Imported from vendor U-Boot linux-6.1-stan-rkr5 tag with minor
adjustments for mainline.
Signed-off-by: Lin Jinhan <troy.lin@rock-chips.com>
Signed-off-by: Jonas Karlman <jonas@kwiboo.se>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>