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/arch/arm/mach-exynos/include/mach/spl.h b/arch/arm/mach-exynos/include/mach/spl.h
index 0c480ac..a5d13fa 100644
--- a/arch/arm/mach-exynos/include/mach/spl.h
+++ b/arch/arm/mach-exynos/include/mach/spl.h
@@ -42,10 +42,10 @@
 	u32		mem_iv_size;	/* Memory channel interleaving size */
 	enum ddr_mode	mem_type;	/* Type of on-board memory */
 	/*
-	 * U-boot size - The iROM mmc copy function used by the SPL takes a
-	 * block count paramter to describe the u-boot size unlike the spi
-	 * boot copy function which just uses the u-boot size directly. Align
-	 * the u-boot size to block size (512 bytes) when populating the SPL
+	 * U-Boot size - The iROM mmc copy function used by the SPL takes a
+	 * block count paramter to describe the U-Boot size unlike the spi
+	 * boot copy function which just uses the U-Boot size directly. Align
+	 * the U-Boot size to block size (512 bytes) when populating the SPL
 	 * table only for mmc boot.
 	 */
 	u32		uboot_size;