drm: atmel-hlcdc: add missing MACROs for register fields

Signed-off-by: Boris BREZILLON <boris.brezillon@free-electrons.com>
drm: atmel-hlcdc: check position and size consistency

Signed-off-by: Boris BREZILLON <boris.brezillon@free-electrons.com>
drm: atmel-hlcdc: fix status flag update

Signed-off-by: Boris BREZILLON <boris.brezillon@free-electrons.com>
drm: atmel-hlcdc: add missing call to finished callback

Signed-off-by: Boris BREZILLON <boris.brezillon@free-electrons.com>
drm: atmel-hlcdc: disable the layer when an overflow occurs

Signed-off-by: Boris BREZILLON <boris.brezillon@free-electrons.com>