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/gma500/framebuffer.c b/drivers/gpu/drm/gma500/framebuffer.c
index 830dfdd6b..78733b5 100644
--- a/drivers/gpu/drm/gma500/framebuffer.c
+++ b/drivers/gpu/drm/gma500/framebuffer.c
@@ -725,10 +725,7 @@
 	if (dev_priv->backlight_property)
 		return 0;
 
-	backlight = drm_property_create(dev, DRM_MODE_PROP_RANGE,
-							"backlight", 2);
-	backlight->values[0] = 0;
-	backlight->values[1] = 100;
+	backlight = drm_property_create_range(dev, 0, "backlight", 0, 100);
 
 	dev_priv->backlight_property = backlight;