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/imgtec/malta/malta.c b/board/imgtec/malta/malta.c
index e31331a..3a9e780 100644
--- a/board/imgtec/malta/malta.c
+++ b/board/imgtec/malta/malta.c
@@ -93,7 +93,7 @@
 {
 	enum core_card core;
 
-	malta_lcd_puts("U-boot");
+	malta_lcd_puts("U-Boot");
 	puts("Board: MIPS Malta");
 
 	core = malta_core_card();