sunxi: Add sun4i support

sunxi: Add sun4i support

Add support for the Allwinner A10 SoC also known as the Allwinner sun4i family,
and add the Cubieboard board which uses the A10 SoC.

Compared to sun7 only the DRAM controller is a bit different:
-Controller reset bits are inverted, but only for Rev. A
-Different hpcr values
-No MBUS on sun4i
-Various other initialization changes

Signed-off-by: Henrik Nordstrom <henrik@henriknordstrom.net>
Signed-off-by: Stefan Roese <sr@denx.de>
Signed-off-by: Oliver Schinagl <oliver@schinagl.nl>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Ian Campbell <ijc@hellion.org.uk>