extcon: Release locking when sending the notification of connector state

Previously, extcon used the spinlock before calling the notifier_call_chain
to prevent the scheduled out of task and to prevent the notification delay.
When spinlock is locked for sending the notification, deadlock issue
occured on the side of extcon consumer device. To fix this issue,
extcon consumer device should always use the work. it is always not
reasonable to use work.

To fix this issue on extcon consumer device, release locking when sending
the notification of connector state.

Fixes: ab11af04 ("extcon: Add the synchronization extcon APIs to support the notification")
Cc: stable@vger.kernel.org
Cc: Roger Quadros <rogerq@ti.com>
Cc: Kishon Vijay Abraham I <kishon@ti.com>
Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>