V4L/DVB: omap24xxcam: potential buffer overflow

The previous loop goes until last == VIDEO_MAX_FRAME, so this could
potentially go one past the end of the loop.

Signed-off-by: Dan Carpenter <error27@gmail.com>
Acked-by: Sakari Ailus <sakari.ailus@maxwell.research.nokia.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>