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/configs/TQM5200.h b/include/configs/TQM5200.h
index 342fdfe..535dc6e 100644
--- a/include/configs/TQM5200.h
+++ b/include/configs/TQM5200.h
@@ -334,7 +334,7 @@
  *
  * Please notice, that the resulting clock frequency could differ from the
  * configured value. This is because the I2C clock is derived from system
- * clock over a frequency divider with only a few divider values. U-boot
+ * clock over a frequency divider with only a few divider values. U-Boot
  * calculates the best approximation for CONFIG_SYS_I2C_SPEED. However the calculated
  * approximation allways lies below the configured value, never above.
  */