ARM: imx: fix error handling in ipu device registration

If we fail to allocate struct platform_device pdev we
dereference it after the goto label err.

This bug was found using coccinelle.

Fixes: afa77ef3

 (ARM: mx3: dynamically allocate "ipu-core" devices)
Signed-off-by: Emil Goode <emilgoode@gmail.com>
Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: Shawn Guo <shawn.guo@freescale.com>
Signed-off-by: Olof Johansson <olof@lixom.net>