media: coda/imx-vdoa: Remove irq member from vdoa_data struct

The 'irq' member of the vdoa_data struct is only used inside probe,
so there is no need for it. Use a local variable 'ret' instead.

Signed-off-by: Fabio Estevam <fabio.estevam@nxp.com>
Reviewed-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>