UPSTREAM: extcon: Add resource-managed functions to register extcon notifier

UPSTREAM: extcon: Add resource-managed functions to register extcon notifier

This patch adds the resource-managed functions for register/unregister
the extcon notifier with the id of each external connector. This function
will make it easy to handle the extcon notifier.

- int devm_extcon_register_notifier(struct device *dev,
				struct extcon_dev *edev, unsigned int id,
				struct notifier_block *nb);
- void devm_extcon_unregister_notifier(struct device *dev,
				struct extcon_dev *edev, unsigned int id,
				struct notifier_block *nb);

Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>
(cherry picked from commit 58f386560a68dd98bd6744a28fc853eef11faebe
  git://git.kernel.org/pub/scm/linux/kernel/git/chanwoo/extcon.git extcon-next)
Signed-off-by: Guenter Roeck <groeck@chromium.org>
Change-Id: I852184d12dc4a03b6d526112e998b087931726e5
Signed-off-by: Chris Zhong <zyw@rock-chips.com>