This driver only uses managed resources, except for the delayed work, if
it is used.

Use devm_delayed_work_autocancel() to also manage the delayed work.
The error handling path of the probe and the remove function can both be
removed.

This saves a few lines of code.
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Reviewed-by: Adam Thomson <Adam.Thomson.Opensource@diasemi.com>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>