Convert to use devm_ functions to reduce code size and simplify the code.

Cc: Uwe Kleine-Koenig <u.kleine-koenig@pengutronix.de>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Acked-by: Uwe Kleine-Koenig <u.kleine-koenig@pengutronix.de>