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/bf561-acvilon.h b/include/configs/bf561-acvilon.h
index 92251fc..31862da 100644
--- a/include/configs/bf561-acvilon.h
+++ b/include/configs/bf561-acvilon.h
@@ -1,5 +1,5 @@
 /*
- * U-boot - Configuration file for BF561 Acvilon System On Module
+ * U-Boot - Configuration file for BF561 Acvilon System On Module
  * For more information please go to http://www.niistt.ru/
  */