This patch moves the 'struct extcon_dev' of extcon subsystem
to driver/extcon/extcon.h header file because the struct extcon_dev have to
be handled by extcon API to guarantee the consistency of strcut extcon_dev.
If external drivers are able to touch the struct extcon_dev directly, it might
cause the critical and unknown problem.
Signed-off-by: NChanwoo Choi <cw00.choi@samsung.com>

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: NChanwoo Choi <cw00.choi@samsung.com>

This patch split out the resource-managed related functions
from extcon core driver.
Signed-off-by: NChanwoo Choi <cw00.choi@samsung.com>