Hey Amit,
If possible could you try replacing your u-boot image with this file here:
https://sel4.systems/Info/Docs/u-boot-working-rpi3-32bit-v2017.11.bin
Or if you'd rather not use a prebuilt binary, you can find instructions on how to
generate an image like the one linked to above here:
https://docs.sel4.systems/Hardware/Rpi3.html#u-boot
Please let me know if that doesn't work for you.
--
Kofi Doku Atuah
Kernel engineer
DATA61 | CSIRO