arm64: dts: renesas: Add R8A779G0 V4H DBSC5 and RT-VRAM DT nodes

arm64: dts: renesas: Add R8A779G0 V4H DBSC5 and RT-VRAM DT nodes

Describe DBSC5 DRAM controller and RT-VRAM configuration interface
as two new DT nodes in R-Car Gen4 R8A779G0 U-Boot DT extras file.
This node is used by the U-Boot SPL for R8A779G0 SoC, where the
DBSC5 and RT-VRAM drivers bind to these nodes and bring up the
DRAM controller and RT-VRAM settings respectively, so U-Boot
proper can be loaded into DRAM and started on Cortex A76 core.

Signed-off-by: Marek Vasut <marek.vasut+renesas@mailbox.org>