sunxi: A133: add DRAM init code

sunxi: A133: add DRAM init code

This adds preliminary support for the DRAM controller in the Allwinner
A100/A133 SoCs.
This is work in progress, and has rough edges, but works on at least
three different boards. It contains support for DDR4 and LPDDR4.

Signed-off-by: Cody Eksal <masterr3c0rd@epochal.quest>
[Andre: formatting fixes, adapt to mainline, drop unused parameters,
	remove struct struct sunxi_mctl_com_reg, hardcode MR registers,
	switch to mctl_check_pattern(), remove simple DRAM check]
Signed-off-by: Andre Przywara <andre.przywara@arm.com>