power: supply: Add support for MAX14656 USB charger detector

power: supply: Add support for MAX14656 USB charger detector

The MAX14656 USB charger detector, also known as "AL32" is used to detect
the presence and capabilities of attached USB chargers. The device is
attached via I2C plus one interrupt line to signalize events.

The device can be found in LG smartphones like LS665 and LS770, compatible
devices are present in 4th/5th generation Amazon Kindle readers referenced
in source code packages as "Maxim AL32".

The initial version of this driver has been extracted from LG source code
package LGLS665_Android_Lollipop_LS665ZV3, enriched with information from
the Kindle_src_4.1.3 source code package and adapted to the current power
class sysfs interface. Non-Standard Apple chargers which the device may
detect are mapped to the USB Battery Charging Specification Revision 1.2
class USB_DCP.

Signed-off-by: Alexander Kurz <akurz@blala.de>
Signed-off-by: Sebastian Reichel <sre@kernel.org>