compositor: use smoother range for backlight control

now it goes from 0 to 255.

Signed-off-by: Tiago Vignatti <tiago.vignatti@intel.com>
diff --git a/src/compositor.h b/src/compositor.h
index b5ba7b2..16389a6 100644
--- a/src/compositor.h
+++ b/src/compositor.h
@@ -97,7 +97,7 @@
 	void (*destroy)(struct weston_output *output);
 	void (*assign_planes)(struct weston_output *output);
 
-	/* backlight values are on 1-10 range, where higher is brighter */
+	/* backlight values are on 0-255 range, where higher is brighter */
 	uint32_t backlight_current;
 	void (*set_backlight)(struct weston_output *output, uint32_t value);
 	void (*set_dpms)(struct weston_output *output, enum dpms_enum level);