sunxi: a523: Re-use H6/H616 DRAM size detection method

sunxi: a523: Re-use H6/H616 DRAM size detection method

The H6 and H616 DRAM initialisation code recently gained a joint and
improved size detection routine, which helped to avoid the occasional
DRAM size misdetection.

Use the same code for the A523 DRAM initialisation as well, which
suffers from the same misdetection at times.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Reviewed-by: Jernej Skrabec <jernej.skrabec@gmail.com>
Tested-by: Chen-Yu Tsai <wens@kernel.org>