extcon: axp288: Replace open coded acpi_dev_put()

Instead of calling put_device(&adev->dev) where adev is a pointer
to an ACPI device, use specific call, i.e. acpi_dev_put().

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>