sunxi: power: add support for sy8106a driver

SY8106A is a PMIC which is used on the Allwinner
H3 Orange Pi Pc and Plus board. The VOUT1_SEL register is
implemented to set the default V-CPU voltage to 1200 mV.

This driver is required to ensure the SY8106A V-CPU
voltage is set to 1200 mV after a software reset. On cold
boot the default SY8106A output voltage is selected to be
1200 mV by a pair of resistors on the Orange Pi PC and Plus.

Signed-off-by: Jelle van der Waa <jelle@vdwaa.nl>
Tested-by: Siarhei Siamashka <siarhei.siamashka@gmail.com>
Acked-by: Siarhei Siamashka <siarhei.siamashka@gmail.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>