Update extcon for 3.11

This patchset modify small fix of extcon core driver and add new extcon
driver for Palmas device which is USB tranceiver device. Also, support
OF helper API to get the name of extcon device(producer driver) on extcon
consumer driver.

Detailed description for patchset:
1. Modify extcon-class driver
- Change permission 'state' sysfs entry(rw->r)
- Use EXPORT_SYMBOL_GPL for exported functions
- Fix bug null pointer when call extcon_unregister_interest

2. Modify Kconfig of extcon
- Change the extcon config type to bool from module. If extcon
is built as module and then extcon consumer driver uses API of,
extcon, compiler happen "undefined reference to" build error.

3. Add new extcon driver for Palmas device and OF helper API
- Add new extcon drvier for Palmas which is USB tranceiver device
- Add OF(OpenFirmware) Helper API which is of_extcon_get_extcon_dev()
  This helper API get the extcon device name on extcon consumer device.
extcon: Add an API to get extcon device from dt node

Added an API of_extcon_get_extcon_dev() to be used by drivers to get
extcon device in the case of dt boot (this can be used instead of
extcon_get_extcon_dev()).

Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>
Signed-off-by: Myungjoo Ham <myungjoo.ham@samsung.com>
4 files changed