ARM64: zynqmp: Add USB boot mode

Add USB boot mode.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
diff --git a/arch/arm/include/asm/arch-zynqmp/hardware.h b/arch/arm/include/asm/arch-zynqmp/hardware.h
index bcb2434..10d67d0 100644
--- a/arch/arm/include/asm/arch-zynqmp/hardware.h
+++ b/arch/arm/include/asm/arch-zynqmp/hardware.h
@@ -69,6 +69,7 @@
 #define SD_MODE1	0x00000005 /* sd 1 */
 #define NAND_MODE	0x00000004
 #define EMMC_MODE	0x00000006
+#define USB_MODE	0x00000007
 #define JTAG_MODE	0x00000000
 #define BOOT_MODE_USE_ALT	0x100
 #define BOOT_MODE_ALT_SHIFT	12