drm/vboxvideo: Remove unnecessary include statements for drm_crtc_helper.h

Several source files include drm_crtc_helper.h without needing it or
only to get its transitive include statements; leading to unnecessary
compile-time dependencies.

Directly include required headers and drop drm_crtc_helper.h where
possible.

Signed-off-by: Thomas Zimmermann <[e-mail]>
Reviewed-by: Sam Ravnborg <[e-mail]>
Acked-by: Jani Nikula <[e-mail]>
Acked-by: Alex Deucher <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]

drivers/gpu/drm/vboxvideo/vbox_drv.c

···
 #include <linux/vt_kern.h>
 
 #include <drm/drm_aperture.h>
-#include <drm/drm_crtc_helper.h>
 #include <drm/drm_drv.h>
 #include <drm/drm_fbdev_generic.h>
 #include <drm/drm_file.h>
 #include <drm/drm_ioctl.h>
 #include <drm/drm_managed.h>
+#include <drm/drm_modeset_helper.h>
 #include <drm/drm_module.h>
 
 #include "vbox_drv.h"

drivers/gpu/drm/vboxvideo/vbox_main.c

···
 #include <linux/pci.h>
 #include <linux/vbox_err.h>
 
-#include <drm/drm_crtc_helper.h>
 #include <drm/drm_damage_helper.h>
 
 #include "vbox_drv.h"