arm: mach-k3: j721e: Rename BOOT_DEVICE_USB to BOOT_DEVICE_DFU

J721e does not support USB Host MSC boot, but only supports DFU boot.
Since BOOT_DEVICE_USB is often used for host boot mode and
BOOT_DEVICE_DFU is used for DFU boot, rename BOOT_DEVICE_USB macro to
BOOT_DEVICE_DFU

Signed-off-by: Vignesh Raghavendra <vigneshr@ti.com>
Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>

arch/arm/mach-k3/include/mach/j721e_spl.h

@@ -18,7 +18,7 @@
 /* With BootMode B = 1 */
 #define BOOT_DEVICE_MMC2		0x10
 #define BOOT_DEVICE_MMC1		0x11
-#define BOOT_DEVICE_USB			0x12
+#define BOOT_DEVICE_DFU			0x12
 #define BOOT_DEVICE_UFS			0x13
 #define BOOT_DEVIE_GPMC			0x14
 #define BOOT_DEVICE_PCIE		0x15