drm: omapdrm: connector-analog-tv: Remove tvc_of_match forward declaration

The tvc_of_match variable is never referenced before its definition.
Remove the forward declaration.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Sebastian Reichel <sebastian.reichel@collabora.co.uk>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>