drm/virtio: Drop dummy gamma table support

#define XRES_MAX  8192

#define YRES_MAX  8192

static void virtio_gpu_crtc_gamma_set(struct drm_crtc *crtc,

				      u16 *red, u16 *green, u16 *blue,

				      uint32_t start, uint32_t size)

{

	/* TODO */

}

static void

virtio_gpu_hide_cursor(struct virtio_gpu_device *vgdev,

		       struct virtio_gpu_output *output)

static const struct drm_crtc_funcs virtio_gpu_crtc_funcs = {

	.cursor_set2            = virtio_gpu_crtc_cursor_set,

	.cursor_move            = virtio_gpu_crtc_cursor_move,

	.gamma_set              = virtio_gpu_crtc_gamma_set,

	.set_config             = drm_atomic_helper_set_config,

	.destroy                = drm_crtc_cleanup,

		return PTR_ERR(plane);

	drm_crtc_init_with_planes(dev, crtc, plane, NULL,

				  &virtio_gpu_crtc_funcs, NULL);

	drm_mode_crtc_set_gamma_size(crtc, 256);

	drm_crtc_helper_add(crtc, &virtio_gpu_crtc_helper_funcs);

	plane->crtc = crtc;