extcon: Set platform drvdata in gpio_extcon_probe() and fix irq leak

Add missing platform_set_drvdata() in gpio_extcon_probe(), otherwise calling
platform_get_drvdata in gpio_extcon_remove() returns NULL.

Also add missing free_irq call in gpio_extcon_remove().

Signed-off-by: Axel Lin <axel.lin@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>