drm: get cea video id code for a given display mode

This patch adds support for getting CEA Video ID Code for a given
display mode after matching with edid_cea_modes list. Its index in
the list added with one, gives the desired code.

This exported function will be used by hdmi drivers for composing
AVI info frame data.

Signed-off-by: Stephane Marchesin <marcheu@chromium.org>
Signed-off-by: Rahul Sharma <rahul.sharma@samsung.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h
index 49dd8c2..1f5f1d6 100644
--- a/include/drm/drm_crtc.h
+++ b/include/drm/drm_crtc.h
@@ -1037,6 +1037,7 @@
 extern int drm_mode_gamma_set_ioctl(struct drm_device *dev,
 				    void *data, struct drm_file *file_priv);
 extern u8 *drm_find_cea_extension(struct edid *edid);
+extern u8 drm_match_cea_mode(struct drm_display_mode *to_match);
 extern bool drm_detect_hdmi_monitor(struct edid *edid);
 extern bool drm_detect_monitor_audio(struct edid *edid);
 extern int drm_mode_page_flip_ioctl(struct drm_device *dev,