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/t208xqds/eth_t208xqds.c b/board/freescale/t208xqds/eth_t208xqds.c
index f08cff2..e92b5d3 100644
--- a/board/freescale/t208xqds/eth_t208xqds.c
+++ b/board/freescale/t208xqds/eth_t208xqds.c
@@ -600,7 +600,7 @@
 	case 0x66:
 	case 0x67:
 		/*
-		 * XFI does not need a PHY to work, but to avoid U-boot use
+		 * XFI does not need a PHY to work, but to avoid U-Boot use
 		 * default PHY address which is zero to a MAC when it found
 		 * a MAC has no PHY address, we give a PHY address to XFI
 		 * MAC, and should not use a real XAUI PHY address, since