[media] media: davinci: vpbe: return error code on error in vpbe_display_g_crop()

We have assigned error code to 'ret' if crop->type is not
V4L2_BUF_TYPE_VIDEO_OUTPUT, but never use it.
We'd better return the error code on this error.

Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Acked-by: Prabhakar Lad <prabhakar.lad@ti.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>