sun6i: Add basic axp221 driver

The A31 uses the AXP221 pmic for various voltages.

Signed-off-by: Oliver Schinagl <oliver@schinagl.nl>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
sun6i: Add clock_init_safe() function

This is a preparation patch for adding SPL support.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
sun6i: SPL hack do not set PLL1 speed for now

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
sun6i: Add cpucfg register definitions

Signed-off-by: Hans de Goede <hdegoede@redhat.com>