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/board/tqc/tqma6/tqma6.c b/board/tqc/tqma6/tqma6.c
index 8656782..7fc57da 100644
--- a/board/tqc/tqma6/tqma6.c
+++ b/board/tqc/tqma6/tqma6.c
@@ -77,7 +77,7 @@
 
 /*
  * According to board_mmc_init() the following map is done:
- * (U-boot device node)    (Physical Port)
+ * (U-Boot device node)    (Physical Port)
  * mmc0                    eMMC (SD3) on TQMa6
  * mmc1 .. n               optional slots used on baseboard
  */