drm/meson: Fix an un-handled error path in 'meson_drv_bind_master()'

'drm_vblank_init()' can fail. So handle this (unlikely) error.

Fixes: bbbe775ec5b5 ("drm: Add support for Amlogic Meson Graphic Controller")
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Acked-by: Neil Armstrong <narmstrong@baylibre.com>
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Link: https://patchwork.freedesktop.org/patch/msgid/6cbf3d70ac3904489c7194c895225c4103aebb96.1520885192.git.christophe.jaillet@wanadoo.fr

drivers/gpu/drm/meson/meson_drv.c

@@ -222,7 +222,10 @@ static int meson_drv_bind_master(struct device *dev, bool has_components)
 
 	priv->vsync_irq = platform_get_irq(pdev, 0);
 
-	drm_vblank_init(drm, 1);
+	ret = drm_vblank_init(drm, 1);
+	if (ret)
+		goto free_drm;
+
 	drm_mode_config_init(drm);
 	drm->mode_config.max_width = 3840;
 	drm->mode_config.max_height = 2160;