f_fastboot.c : on USB boot default to fastboot mode

drivers/usb/gadget/f_fastboot.c

@@ -1567,8 +1567,8 @@ void board_fastboot_setup(void)
 		break;
 	case USB_BOOT:
 		printf("Detect USB boot. Will enter fastboot mode!\n");
-		if (!getenv("bootcmd"))
-			setenv("bootcmd", "fastboot 0");
+		setenv("bootcmd", "fastboot 0");
+		break;
 #endif /*CONFIG_FASTBOOT_STORAGE_MMC*/
 	default:
 		printf("unsupported boot devices\n");