DRAM controller magic values cleanup

This patch tries to cleanup as much of the magic values in dram.c as
possible. Obviously for some registers we have no information so cannot
fill those in. No actual code changes took place. This patch is however
based on the most recent dram.c; e.g. from A20.

Signed-off-by: Oliver Schinagl <oliver@schinagl.nl>
Add more sun7i specifics from drop

This adds a few more specifics from sun7i. Command Rate was added, which
could tune memory slightly. Some code from Powermanamgement 'super
standby' that most likly can be cleared later if found to be unused.

Signed-off-by: Oliver Schinagl <oliver@schinagl.nl>