Thank you very much Chester for your reply.
Actually the thing was that I was compiling the project using default stack size that's why micro was not able to return from function and was pointing to some other location. When I changed the stack size the code for UART Boot loader executed and I have debugged it successfully.
Now I am trying to change the peripheral and want to use SSI0 but again the same thing is happening.
One thing I noticed that the program starts from ResetISR, in disassembly window when using UART the linkage of _c_int00: was with UartSend() function but when I am commenting the flag #define UART_ENABLE_UPDATE and uncommenting #define SSI_ENABLE_UPDATE the linkage of _c_int00: is with CheckForceUpdate and I am not able to single step in it.