MAINTAINERS: add a maintainer for the atmel-hlcdc DRM driver

Add myself as the maintainer of the atmel-hlcdc DRM driver.

Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>