As everything else is now handled by devm managed releases the
triggered buffer setup and IIO device registration can also be
moved over to their devm forms allowing dropping of remove().

Only user of drvdata associated with the struct device was the
remove function, so also drop the platform_set_drvdata() call.
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Nuno Sá <nuno.sa@analog.com>
Link: https://lore.kernel.org/r/20221016170950.387751-6-jic23@kernel.org