[meta-freescale] Changing the IMX6 UART clock speed?

[Alagarsamy, Siva]

Hi,
 I need a change the UART clock speed in IMX6 to 50MHz from the current 80MHz.  I understand there is a main clock that drives all  subsystem clocks. 
How do I change the main clock to get the 50MHz clock for the UART.  Is this something I can change in the u-boot or kernel configuration or is it something in the kernel code that I have to change?

Thanks,
Siva