extcon: Fix extcon_cable_get_state() from getting old state after notification

Currently the extcon code notifiers the interested listeners
before it updates the extcon state with the new state.
This will cause the listeners that use extcon_cable_get_state()
to get the stale state and loose the new state.

Fix this by first changing the extcon state variable and then
notifying listeners.

Signed-off-by: Roger Quadros <rogerq@ti.com>
Tested-by: Ivan T. Ivanov <ivan.ivanov@linaro.org>
Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>