[media] MAINTAINERS: Add entry for the Aptina PLL library

Add a maintainers entry for the Aptina PLL library, and rename the
Aptina sensors entries to make it clear they refer to Aptina camera
sensors.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>