[media] media: fix MEDIA_IOC_DEVICE_INFO return code

The MEDIA_IOC_DEVICE_INFO ioctl was returning a positive value rather
than a negative error code when failing to copy output parameter to
user-space.

Tested by compilation only.

Signed-off-by: Nicolas Thery <nicolas.thery@st.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>