V4L/DVB (10110): v4l2-ioctl: Fix warnings when using .unlocked_ioctl = __video_ioctl2

This patch fixes this warning:

drivers/media/video/gspca/gspca.c:1811: warning: initialization from incompatible pointer type

The reason is that the returned argument should be a long, not an
integer.

Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>