drm: Remove drmP.h include from drm_kms_helper_common.c

An easy one as a drive-by.
Reviewed-by: NGustavo Padovan <gustavo.padovan@collabora.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170308141257.12119-6-daniel.vetter@ffwll.ch

drivers/gpu/drm/drm_kms_helper_common.c

@@ -25,8 +25,7 @@
  *
  */
 
-#include <drm/drmP.h>
-#include <drm/drm_fb_helper.h>
+#include <linux/module.h>
 
 #include "drm_crtc_helper_internal.h"