Fix a few -pedantic warnings

We're not enabling -pedantic by default, but a quick test brought up a few
issues that we should fix.
diff --git a/src/libbacklight.h b/src/libbacklight.h
index cea34c2..0c32671 100644
--- a/src/libbacklight.h
+++ b/src/libbacklight.h
@@ -10,7 +10,7 @@
 enum backlight_type {
 	BACKLIGHT_RAW,
 	BACKLIGHT_PLATFORM,
-	BACKLIGHT_FIRMWARE,
+	BACKLIGHT_FIRMWARE
 };
 
 struct backlight {