[media] MAINTAINERS: add entry for OV5640 sensor driver

Add maintainer entry for the OV5640 V4L2 sensor driver.

Signed-off-by: Steve Longerbeam <steve_longerbeam@mentor.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>