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/bsc9131rdb/README b/board/freescale/bsc9131rdb/README
index 4902b98..c840597 100644
--- a/board/freescale/bsc9131rdb/README
+++ b/board/freescale/bsc9131rdb/README
@@ -86,9 +86,9 @@
 --------------------
 NAND boot
 
-Building U-boot
+Building U-Boot
 --------------
-To build the u-boot for BSC9131RDB:
+To build the U-Boot for BSC9131RDB:
 1. NAND Flash with sysclk 66MHz(J16 on RDB closed, default)
 	make BSC9131RDB_NAND
 2. NAND Flash with sysclk 100MHz(J16 on RDB open)
@@ -123,7 +123,7 @@
 
 Flashing Images
 ---------------
-To place a new u-boot image in the NAND flash and then boot
+To place a new U-Boot image in the NAND flash and then boot
 with that new image temporarily, use this:
 	tftp 1000000 u-boot-nand.bin
 	nand erase 0 100000