sunxi: fix CCM MBUS N factor interpretation

N is stored as the exponent of a power of two, so 8 needs to return 3,
4 needs to return 2, etc.

Signed-off-by: Emilio López <emilio@elopez.com.ar>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
sunxi: fast MBUS support on sun7i

For qualifying hardware, we can run MBUS at 400MHz without risking
stability if we raise the DCDC3 voltage to 1.3V

Signed-off-by: Emilio López <emilio@elopez.com.ar>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
sunxi: enable 400MHz MBUS on Cubieboard2 and Cubietruck

This has been tested on 50 pieces of Cubieboard2 by Cubietech and no
issues of any kind were reported.

Signed-off-by: Emilio López <emilio@elopez.com.ar>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>