[media] mark myself as mainainer for camera on N900

Mark and Sakari as maintainers for Nokia N900 camera pieces.

Signed-off-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>