media: omap4iss: return error code when omap4iss_get() failed

If omap4iss_get() failed, it need return error code in iss_probe().

Fixes: 59f0ad80 ("[media] v4l: omap4iss: Add support for OMAP4...")
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>