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/include/linux/usb/cdc.h b/include/linux/usb/cdc.h
index c1d039c..442316b 100644
--- a/include/linux/usb/cdc.h
+++ b/include/linux/usb/cdc.h
@@ -5,7 +5,7 @@
  * notably ethernet adapters and various modems.  It's used mostly with
  * firmware based USB peripherals.
  *
- * Ported to U-boot by: Thomas Smits <ts.smits@gmail.com> and
+ * Ported to U-Boot by: Thomas Smits <ts.smits@gmail.com> and
  *                      Remy Bohmer <linux@bohmer.net>
  */