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/freescale/mpc837xerdb/README b/board/freescale/mpc837xerdb/README
index cfb6efa..12df2f2 100644
--- a/board/freescale/mpc837xerdb/README
+++ b/board/freescale/mpc837xerdb/README
@@ -84,7 +84,7 @@
 
 	tftp $loadaddr u-boot.bin
 
-5.1 Reflash U-boot Image using U-boot
+5.1 Reflash U-Boot Image using U-Boot
 
 	tftp $loadaddr u-boot.bin
 	protect off fe000000 fe0fffff