Add Renesas R-Car Gen4 DBSC5 DRAM controller driver. This driver is currently
capable of bringing LPDDR5 DRAM on Renesas R-Car V4H Whitehawk board. Further
boards can be supported by supplying board specific DRAM configuration data
via dbsc5_get_board_data(). Support for R-Car V4M is not implemented, however
the driver is already mostly prepared to support this SoC.

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

Add support for Schneider Electric RZ/N1D and RZ/N1S boards, which
are based on the Reneasas RZ/N1 SoC devices.

The intention is to support both boards using a single defconfig, and to
handle the differences at runtime.

Signed-off-by: Ralph Siemsen <ralph.siemsen@linaro.org>
Reviewed-by: Marek Vasut <marek.vasut+renesas@mailbox.org>