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/drivers/net/lan91c96.c b/drivers/net/lan91c96.c
index c4dd01e..3526876 100644
--- a/drivers/net/lan91c96.c
+++ b/drivers/net/lan91c96.c
@@ -1,7 +1,7 @@
 /*------------------------------------------------------------------------
  * lan91c96.c
  * This is a driver for SMSC's LAN91C96 single-chip Ethernet device, based
- * on the SMC91111 driver from U-boot.
+ * on the SMC91111 driver from U-Boot.
  *
  * (C) Copyright 2002
  * Sysgo Real-Time Solutions, GmbH <www.elinos.com>