Merge tag 'extcon-next-for-4.15' of git://git.kernel.org/pub/scm/linux/kernel/git/chanwoo/extcon into usb-next

Chanwoo writes:

Update extcon for 4.15

Detailed description for this pull request:
1. Split out extcon header file for consumer and provider device
: The extcon has two type of extcon devices as following.
- 'extcon provider deivce' adds new extcon device and detect
the state/properties of external connector. Also, it notifies the
state/properties to the extcon consumer device.
- 'extcon consumer device' gets the change state/properties
from extcon provider device.

Prior to that, include/linux/extcon.h contains all exported API
for both provider and consumer device driver. To clarify the meaning
of header file and to remove the wrong use-case on consumer device.
- include/linux/extcon-provider.h includes API for the provider device driver.
- include/linux/extcon.h includes the API for the consumer device driver.

2. Support the SmartDock accessory on extcon-max77843.c device driver
- Support the SmartDock accessory which detects following connectors
 at the same time.
 : USB host throught USB hub for mouse, keyboard and so on.
 : MHL connector for video output.
 : Charger connector for battery charging.
- It tested with Unitek Y-2165 MHL+OTG Hub Smart Phone Dock.

3. Fix the minor issue of extcon driver
- Delete the unneeded initialization in extcon-max14577.
- Make extcon_info static const in order to fix the warning.