iio: core: drop devm_iio_device_unregister() API call

It's unused so far, so it can be removed. Also makes sense to remove it
to discourage weird uses of this call during review.

Signed-off-by: Alexandru Ardelean <[e-mail]>
Signed-off-by: Jonathan Cameron <[e-mail]>

Documentation/driver-api/driver-model/devres.rst

···
   devm_iio_device_alloc()
   devm_iio_device_free()
   devm_iio_device_register()
-  devm_iio_device_unregister()
   devm_iio_kfifo_allocate()
   devm_iio_kfifo_free()
   devm_iio_triggered_buffer_setup()

drivers/iio/industrialio-core.c

···
 EXPORT_SYMBOL_GPL(__devm_iio_device_register);
 
 /**
- * devm_iio_device_unregister - Resource-managed iio_device_unregister()
- * @dev:	Device this iio_dev belongs to
- * @indio_dev:	the iio_dev associated with the device
- *
- * Unregister iio_dev registered with devm_iio_device_register().
- */
-void devm_iio_device_unregister(struct device *dev, struct iio_dev *indio_dev)
-{
-	int rc;
-
-	rc = devres_release(dev, devm_iio_device_unreg,
-			    devm_iio_device_match, indio_dev);
-	WARN_ON(rc);
-}
-EXPORT_SYMBOL_GPL(devm_iio_device_unregister);
-
-/**
  * iio_device_claim_direct_mode - Keep device in direct mode
  * @indio_dev:	the iio_dev associated with the device
  *

include/linux/iio/iio.h

···
  * calls iio_device_register() internally. Refer to that function for more
  * information.
  *
- * If an iio_dev registered with this function needs to be unregistered
- * separately, devm_iio_device_unregister() must be used.
- *
  * RETURNS:
  * 0 on success, negative error number on failure.
  */
···
 	__devm_iio_device_register((dev), (indio_dev), THIS_MODULE);
 int __devm_iio_device_register(struct device *dev, struct iio_dev *indio_dev,
 			       struct module *this_mod);
-void devm_iio_device_unregister(struct device *dev, struct iio_dev *indio_dev);
 int iio_push_event(struct iio_dev *indio_dev, u64 ev_code, s64 timestamp);
 int iio_device_claim_direct_mode(struct iio_dev *indio_dev);
 void iio_device_release_direct_mode(struct iio_dev *indio_dev);