W1: Add device tree support to MXC onewire master.

Signed-off-by: Martin Fuzzey <mfuzzey@parkeon.com>
Acked-by: Sascha Hauer <s.hauer@pengutronix.de>
Acked-by: Evgeniy Polyakov <zbr@ioremap.net>
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>