extcon: max8997: Add missing kfree for info->edev in max8997_muic_remove()

extcon_dev_unregister(info->edev) doest not free info->edev, we need to call
kfree(info->edev) here.

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