rockchip: rk3399: add Support NanoPi R4S 1GB DDR3 Version

[h3lmut]

The NanoPi R4S 1GB version (rk3399) doesnt boot up with current u-boot. Armbian team has done some patches which will work with both versions (1GB and 4GB)

Github Pr:
https://github.com/anaelorlinski/OpenWrt-NanoPi-R2S-R4S-Builds/commit/9d836044340ddef53f5d9f1946ac48c946a78284

From 1bc90230df5cd55513268f2f7a43abdbad1161b5 Mon Sep 17 00:00:00 2001
From: hmz007 <hmz007 at gmail.com>
Date: Sat, 19 Dec 2020 19:39:14 +0800
Subject: [PATCH 3/4] ram: rk3399: Add support for multiple DDR types

Move rockchip,sdram-params to named subnode to include
multiple sdram parameters, and then read the parameters
(by subnode name, first subnode or current node) before
rk3399_dmc_init().

Signed-off-by: hmz007 <hmz007 at gmail.com>
---
 arch/arm/dts/rk3399-sdram-ddr3-1333.dtsi      |  6 ++-
 arch/arm/dts/rk3399-sdram-ddr3-1600.dtsi      |  5 +-
 arch/arm/dts/rk3399-sdram-ddr3-1866.dtsi      |  6 ++-
 .../arm/dts/rk3399-sdram-lpddr3-2GB-1600.dtsi |  3 ++
 .../arm/dts/rk3399-sdram-lpddr3-4GB-1600.dtsi |  3 ++
 .../rk3399-sdram-lpddr3-samsung-4GB-1866.dtsi |  3 ++
 arch/arm/dts/rk3399-sdram-lpddr4-100.dtsi     |  3 ++
 drivers/ram/rockchip/sdram_rk3399.c           | 49 +++++++++++++++----
 8 files changed, 64 insertions(+), 14 deletions(-)

diff --git a/arch/arm/dts/rk3399-sdram-ddr3-1333.dtsi b/arch/arm/dts/rk3399-sdram-ddr3-1333.dtsi
index 7fae249536..dad5b7fbd4 100644
--- a/arch/arm/dts/rk3399-sdram-ddr3-1333.dtsi
+++ b/arch/arm/dts/rk3399-sdram-ddr3-1333.dtsi