drm/edid: Add drm_rgb_quant_range_selectable()

drm_rgb_quant_range_selectable() will report whether the monitor
claims to support for RGB quantization range selection.

The information can be found in the CEA Video capability block.

v2: s/quantzation/quantization/ in the comment

Reviewed-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Acked-by: David Airlie <airlied@linux.ie>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h
index 00d78b5..30892dc 100644
--- a/include/drm/drm_crtc.h
+++ b/include/drm/drm_crtc.h
@@ -1033,6 +1033,7 @@
 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 bool drm_rgb_quant_range_selectable(struct edid *edid);
 extern int drm_mode_page_flip_ioctl(struct drm_device *dev,
 				    void *data, struct drm_file *file_priv);
 extern struct drm_display_mode *drm_cvt_mode(struct drm_device *dev,