When FIT image is used, a single image provides kernel, device
tree and optionally ramdisk. Argc and argv need to be adjusted
to support this.
Test cases:
1. Booting with legacy images
2. Booting with legacy images without initrd
3. Booting with FIT image
Test commands:
1. pxe get && pxe boot
2. sysboot
Signed-off-by: York Sun <york.sun@nxp.com>
Signed-off-by: Wenbin Song <wenbin.song@nxp.com>