[PATCH v6 4/9] mfd: axp20x: Split the driver into core and i2c bits

The axp20x driver assumes the device is i2c based. This is not the case with later chips, which use a proprietary 2 wire serial bus by Allwinner called "Reduced Serial Bus". This patch follows the example of mfd/wm831x and splits it into an interface independent core, and an i2c specific glue

[PATCH v6 4/9] mfd: axp20x: Split the driver into core and i2c bits

The axp20x driver assumes the device is i2c based. This is not the case with later chips, which use a proprietary 2 wire serial bus by Allwinner called "Reduced Serial Bus". This patch follows the example of mfd/wm831x and splits it into an interface independent core, and an i2c specific glue