MPC860: quicc_smc_serial_driver change

[nprasad3@gmu.edu]

> 
> Why do you want to add polling mode to an interrupt-driven driver?
> 
I am making an *assumption* here that the person who wrote the driver intended it to be in polling mode if BUF_SIZE = 0 (all interrupt related code gets left out if thats the case including installing the interrupt vector). 

I started with the polling mode driver as I thought it would be easy to get it going on my target first. 

Please let me know if I am missing something.

Thanks
Nirmal