AXP803 Battery Charger Support

[xalius]

I learned a lot more about the PMIC tonight talking to the linux-sunxi kernel developers. The A64 contains a companion Opencores RISC CPU that handles some part of the power-management. During boot this CPU core's code is loaded from a binary and the Linux driver interfaces with it. That means the Linux powermanagement driver does not talk to the PMIC directly, some low level functions, including the I2C interface are handled by that embedded CPU. I am currently figuring out where one can set the battery parameters and in which way they get passed down the layers to the PMIC.

Check for https://linux-sunxi.org/AR100 , https://linux-sunxi.org/Pine64#Boot_sequence