Enabled support for AXP818 in SPL and u-boot.
DCDC1, DCDC2, DCDC3 and DCSC5 are enabled.

Signed-off-by: Vishnu Patekar <vishnupatekar0510@gmail.com>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>