drm: sun4i: Add composite output

Some Allwinner SoCs have an IP called the TV encoder that is used to output
composite and VGA signals. In such a case, we need to use the second TCON
channel.

Add support for that TV encoder.
Reviewed-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>

drivers/gpu/drm/sun4i/Makefile

@@ -9,3 +9,5 @@ sun4i-tcon-y += sun4i_dotclock.o
 
 obj-$(CONFIG_DRM_SUN4I)		+= sun4i-drm.o sun4i-tcon.o
 obj-$(CONFIG_DRM_SUN4I)		+= sun4i_backend.o
+
+obj-$(CONFIG_DRM_SUN4I)		+= sun4i_tv.o