drm: add convenience function to create an range property

Creating a range property is a common pattern, so create
a convenience function for this and use it where appropriate.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/drivers/gpu/drm/i2c/ch7006_drv.c b/drivers/gpu/drm/i2c/ch7006_drv.c
index 07d55df..d3f2e87 100644
--- a/drivers/gpu/drm/i2c/ch7006_drv.c
+++ b/drivers/gpu/drm/i2c/ch7006_drv.c
@@ -252,10 +252,7 @@
 
 	drm_mode_create_tv_properties(dev, NUM_TV_NORMS, ch7006_tv_norm_names);
 
-	priv->scale_property = drm_property_create(dev, DRM_MODE_PROP_RANGE,
-						   "scale", 2);
-	priv->scale_property->values[0] = 0;
-	priv->scale_property->values[1] = 2;
+	priv->scale_property = drm_property_create_range(dev, 0, "scale", 0, 2);
 
 	drm_connector_attach_property(connector, conf->tv_select_subconnector_property,
 				      priv->select_subconnector);