Revert "drivers/gpu/drm/i915/intel_overlay.c needs seq_file.h"

This reverts commit e167976ee7f5fe4b80f7e8f55e087f6c67cf9562,
Since this was already fixed in commit
3bd3c9329973a93fa3ef5e9840f2fd6fa2889e3f some days before this
commit cause seq_file.h to be included twice.

Signed-off-by: Danny Kukawka <danny.kukawka@bisect.de>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/intel_overlay.c

@@ -25,8 +25,6 @@
  *
  * Derived from Xorg ddx, xf86-video-intel, src/i830_video.c
  */
-
-#include <linux/seq_file.h>
 #include "drmP.h"
 #include "drm.h"
 #include "i915_drm.h"