sunxi: DRAM: fix H3 DRAM size display on aarch64

Fix the output of the DRAM size on AArch64 SPLs.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Reviewed-by: Alexander Graf <agraf@suse.de>
Reviewed-by: Simon Glass <sjg@chromium.org>
Acked-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Reviewed-by: Jagan Teki <jagan@openedev.com>