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/wandboard/README b/board/wandboard/README
index c6c0132..6345416 100644
--- a/board/wandboard/README
+++ b/board/wandboard/README
@@ -9,7 +9,7 @@
 For more details about Wandboard, please refer to:
 http://www.wandboard.org/
 
-Building U-boot for Wandboard
+Building U-Boot for Wandboard
 -----------------------------
 
 To build U-Boot for the Wandboard:
@@ -17,7 +17,7 @@
 $ make wandboard_config
 $ make
 
-Flashing U-boot into the SD card
+Flashing U-Boot into the SD card
 --------------------------------
 
 - After the 'make' command completes, the generated 'SPL' binary must be
@@ -36,4 +36,4 @@
 
 - Connect the serial cable to the host PC
 
-- Power up the board and U-boot messages will appear in the serial console.
+- Power up the board and U-Boot messages will appear in the serial console.