arm64: renesas: Make bottom 128 MiB of DRAM available in EL3

arm64: renesas: Make bottom 128 MiB of DRAM available in EL3

In case U-Boot runs in EL3, which is the highest privilege level on ARM64,
there can be no firmware running that would restrict access to the bottom
128 MiB of DRAM. In fact, it is likely that U-Boot would have to load that
firmware into those bottom 128 MiB of DRAM and start that firmware.

Make those bottom 128 MiB of DRAM available in case U-Boot runs in EL3 to
allow loading the firmware to that area.

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