Mediatek DRM Fixes for Linux 5.16

1. Perform NULL pointer check for mtk_hdmi_conf.
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Merge tag 'mediatek-drm-fixes-5.16' of https://git.kernel.org/pub/scm/linux/kernel/git/chunkuang.hu/linux into drm-fixes

Mediatek DRM Fixes for Linux 5.16

1. Perform NULL pointer check for mtk_hdmi_conf.

Signed-off-by: Dave Airlie <airlied@redhat.com>

From: Chun-Kuang Hu <chunkuang.hu@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/1639956861-14873-1-git-send-email-chunkuang.hu@kernel.org

drivers/gpu/drm/mediatek/mtk_hdmi.c

@@ -1224,12 +1224,14 @@ static int mtk_hdmi_bridge_mode_valid(struct drm_bridge *bridge,
 			return MODE_BAD;
 	}
 
-	if (hdmi->conf->cea_modes_only && !drm_match_cea_mode(mode))
-		return MODE_BAD;
+	if (hdmi->conf) {
+		if (hdmi->conf->cea_modes_only && !drm_match_cea_mode(mode))
+			return MODE_BAD;
 
-	if (hdmi->conf->max_mode_clock &&
-	    mode->clock > hdmi->conf->max_mode_clock)
-		return MODE_CLOCK_HIGH;
+		if (hdmi->conf->max_mode_clock &&
+		    mode->clock > hdmi->conf->max_mode_clock)
+			return MODE_CLOCK_HIGH;
+	}
 
 	if (mode->clock < 27000)
 		return MODE_CLOCK_LOW;