imx-drm: convert to componentised device support

Use the componentised device support for imx-drm.  This requires all
the sub-components and the master device to register with the component
device support.

Acked-by: Philipp Zabel <p.zabel@pengutronix.de>
Acked-by: Shawn Guo <shawn.guo@linaro.org>
Reviewed-by: Fabio Estevam <fabio.estevam@freescale.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>