disp: msm: add private mode_seamless flag

This change adds DRM_MODE_SEAMLESS to private flags downstream,
as it was deprecated from drm UAPI. Additionally, this will
update the is_mode_seamless function to access the seamless
flag from private flags.

Change-Id: Idea0b4ac8e71063c000f582d3228bc0a50a6a8e6
Signed-off-by: orion brody <obrody@codeaurora.org>

msm/dsi/dsi_drm.c

@@ -118,7 +118,7 @@ void dsi_convert_to_drm_mode(const struct dsi_display_mode *dsi_mode,
 	drm_mode->private = (int *)dsi_mode->priv_info;
 
 	if (dsi_mode->dsi_mode_flags & DSI_MODE_FLAG_SEAMLESS)
-		drm_mode->flags |= DRM_MODE_FLAG_SEAMLESS;
+		drm_mode->private_flags |= DRM_MODE_FLAG_SEAMLESS;
 	if (dsi_mode->dsi_mode_flags & DSI_MODE_FLAG_DFPS)
 		drm_mode->private_flags |= MSM_MODE_FLAG_SEAMLESS_DYNAMIC_FPS;
 	if (dsi_mode->dsi_mode_flags & DSI_MODE_FLAG_VBLANK_PRE_MODESET)