media: amphion: fix UNUSED_VALUE issue reported by coverity

assign value '-EINVAL' to ret, but the stored value is overwritten
before it can be used

Fixes: 9f599f35

 ("media: amphion: add vpu core driver")
Reviewed-by: Nicolas Dufresne <nicolas.dufresne@collabora.com>
Signed-off-by: Ming Qian <ming.qian@nxp.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>