Since only the the pre-compiled .a files are released for certain packages, the changes done by you in the config file will not have impact.
This is the reason for the linker error.
You could apply the timer related changes to XDK based on reference from EmLib, em_burtc.h file.
Thanks for your hint with the EM libs.
I already tried it without success before, which was the reason for trying the example.
But I came back to it and found my mistake I would like to share with the community.
Problem was that the BURTC is by default in a reset mode, this is also mentioned in the comment of the BURTC_Init function.
The only thing that was missing was to call the "RMU_ResetControl(rmuResetBU, false);" command and release the BURTC from reset.
Thank you all for your help.