drm/edid: Introduce drm_hdmi_avi_infoframe_quant_range()

Pull the logic to populate the quantization range information
in the AVI infoframe into a small helper. We'll be adding a bit
more logic to it, and having it in a central place seems like a
good idea since it's based on the CEA-861 spec.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170111125725.8086-4-ville.syrjala@linux.intel.com
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Acked-by: Eric Anholt <eric@anholt.net>
diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.c b/drivers/gpu/drm/vc4/vc4_hdmi.c
index 5d49bf9..87b5946 100644
--- a/drivers/gpu/drm/vc4/vc4_hdmi.c
+++ b/drivers/gpu/drm/vc4/vc4_hdmi.c
@@ -356,15 +356,11 @@ static void vc4_hdmi_set_avi_infoframe(struct drm_encoder *encoder)
 		return;
 	}
 
-	if (vc4_encoder->rgb_range_selectable) {
-		if (vc4_encoder->limited_rgb_range) {
-			frame.avi.quantization_range =
-				HDMI_QUANTIZATION_RANGE_LIMITED;
-		} else {
-			frame.avi.quantization_range =
-				HDMI_QUANTIZATION_RANGE_FULL;
-		}
-	}
+	drm_hdmi_avi_infoframe_quant_range(&frame.avi,
+					   vc4_encoder->limited_rgb_range ?
+					   HDMI_QUANTIZATION_RANGE_LIMITED :
+					   HDMI_QUANTIZATION_RANGE_FULL,
+					   vc4_encoder->rgb_range_selectable);
 
 	vc4_hdmi_write_infoframe(encoder, &frame);
 }