drm: add at91 lcdc support

Signed-off-by: Boris BREZILLON <boris.brezillon@free-electrons.com>
ARM: at91/dt: add lcdc node definition

Signed-off-by: Boris BREZILLON <boris.brezillon@free-electrons.com>
ARM: at91/dt: move sama5d36ek board to simple-panel def

Signed-off-by: Boris BREZILLON <boris.brezillon@free-electrons.com>
ARM: at91/dt: enable lcdc on sama5d36ek board

Signed-off-by: Boris BREZILLON <boris.brezillon@free-electrons.com>
MAINTAINERS: add AT91 Clock Support entry

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