Hello Aditya Nagal,
You do need to customize u-boot and the device tree so that they reflect the hardware on your board.
My recommendation would be taking a configuration that’s close to your board and making the necessary changes. You can find a guide on customizing the device tree on the following community document:
https://community.nxp.com/docs/DOC-329664
Please consult the i.MX BSP Porting Guide which is available as part of the BSP Releases documentation for more information on how to port the BSP to your custom board including the bootloader.
I hope this information helps!
Regards,