Use correct spelling of "U-Boot"

Correct spelling of "U-Boot" shall be used in all written text
(documentation, comments in source files etc.).

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Heiko Schocher <hs@denx.de>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Minkyu Kang <mk7.kang@samsung.com>
diff --git a/include/configs/novena.h b/include/configs/novena.h
index d5f517c..a541613 100644
--- a/include/configs/novena.h
+++ b/include/configs/novena.h
@@ -1,5 +1,5 @@
 /*
- * Configuration settings for the Novena U-boot.
+ * Configuration settings for the Novena U-Boot.
  *
  * Copyright (C) 2014 Marek Vasut <marex@denx.de>
  *