extcon: Remove unneeded extern keyword from extcon-provider.h

The commit tb7365587f513 ("extcon: Remove unneeded extern keyword
from extcon.h") removes the unneeded extern keyword from extcon header
file. But, The commit tb7365587f513 has missed that deletes 'extern'
keyword from extcon-provider.h. So that it deletes extern keyword
from extcon-provider.h.

Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>
Link: https://lore.kernel.org/r/20200217104728.29330-1-cw00.choi@samsung.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 282

Based on 1 normalized pattern(s):

this software is licensed under the terms of the gnu general public
license version 2 as published by the free software foundation and
may be copied distributed and modified under those terms this
program is distributed in the hope that it will be useful but
without any warranty without even the implied warranty of
merchantability or fitness for a particular purpose see the gnu
general public license for more details

extracted by the scancode license scanner the SPDX license identifier

GPL-2.0-only

has been chosen to replace the boilerplate/reference in 285 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Alexios Zavras <alexios.zavras@intel.com>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190529141900.642774971@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

extcon: 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,
this patch separates into extcon.h and extcon-provider.h.

[Description for include/linux/{extcon.h|extcon-provider.h}]
- extcon.h includes the extcon API and data structure for extcon consumer
device driver. This header file contains the following APIs:
: Register/unregister the notifier to catch the change of extcon device
: Get the extcon device instance
: Get the extcon device name
: Get the state of each external connector
: Get the property value of each external connector
: Get the property capability of each external connector

- extcon-provider.h includes the extcon API and data structure for extcon
provider device driver. This header file contains the following APIs:
: Include 'include/linux/extcon.h'
: Allocate the memory for extcon device instance
: Register/unregister extcon device
: Set the state of each external connector
: Set the property value of each external connector
: Set the property capability of each external connector

Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>
Acked-by: Sebastian Reichel <sebastian.reichel@collabora.co.uk>
Acked-by: Chen-Yu Tsai <wens@csie.org>
Acked-by: Charles Keepax <ckeepax@opensource.cirrus.com>
Acked-by: Lee Jones <lee.jones@linaro.org>
Acked-by: Felipe Balbi <felipe.balbi@linux.intel.com>
Acked-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Acked-by: Kishon Vijay Abraham I <kishon@ti.com>