drm/simpledrm: Use fbdev defaults for shadow buffering

Don't select shadow buffering for the fbdev console explicitly. The
fbdev emulation's heuristic will enable it for any framebuffer with
.dirty callback.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220303205839.28484-2-tzimmermann@suse.de

drivers/gpu/drm/tiny/simpledrm.c

@@ -801,7 +801,6 @@ static int simpledrm_device_init_modeset(struct simpledrm_device *sdev)
 	dev->mode_config.max_width = max_width;
 	dev->mode_config.min_height = mode->vdisplay;
 	dev->mode_config.max_height = max_height;
-	dev->mode_config.prefer_shadow_fbdev = true;
 	dev->mode_config.preferred_depth = sdev->format->cpp[0] * 8;
 	dev->mode_config.funcs = &simpledrm_mode_config_funcs;