drm/exynos: remove exynos_drm_rotator.h

Since its inclusion in 2012 via commit bea8a429 ("drm/exynos: add rotator ipp driver")
this header is not used by any source files and is empty.
Lets just remove it.
Signed-off-by: Corentin Labbe <clabbe@baylibre.com>
Signed-off-by: Inki Dae <inki.dae@samsung.com>

drivers/gpu/drm/exynos/exynos_drm_rotator.h

-/*
- * Copyright (c) 2012 Samsung Electronics Co., Ltd.
- *
- * Authors:
- *	YoungJun Cho <yj44.cho@samsung.com>
- *	Eunchul Kim <chulspro.kim@samsung.com>
- *
- * This program is free software; you can redistribute  it and/or modify it
- * under  the terms of  the GNU General  Public License as published by the
- * Free Software Foundation;  either version 2 of the  License, or (at your
- * option) any later version.
- */
-
-#ifndef	_EXYNOS_DRM_ROTATOR_H_
-#define	_EXYNOS_DRM_ROTATOR_H_
-
-/* TODO */
-
-#endif