media: imx7-media-csi: Propagate the correct error for platform_get_irq()

In the case of platform_get_irq() failure, let's propagate the real error
code instead of a fake one.

Signed-off-by: Fabio Estevam <festevam@gmail.com>
Tested-by: Rui Miguel Silva <rmfrfs@gmail.com>
Reviewed-by: Rui Miguel Silva <rmfrfs@gmail.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>