sunxi: Convert sun4i boards to use auto dram configuration

Currently we've separate detailed dram settings for all sun4i boards, this
moves them over to using auto dram configuration so that we can get rid of
all the per board dram_foo.c files.

Tested-by: Hans de Goede <hdegoede@redhat.com> on a A10-OLinuXino-Lime,
 Chuwi_V7_CW0825 and ba10_tv_box
Tested-by: Zoltan HERPAI <wigyori@uid0.hu> on a pcduino
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Ian Campbell <ijc@hellion.org.uk>