ASoC: da7219-aad: fix usage of device_get_named_child_node()

The documentation for device_get_named_child_node() mentions this
important point:

"
The caller is responsible for calling fwnode_handle_put() on the
returned fwnode pointer.
"

Add fwnode_handle_put() to avoid a leaked reference.

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20240426153033.38500-1-pierre-louis.bossart@linux.intel.com


Signed-off-by: Mark Brown <broonie@kernel.org>