According to chapter 188.8.131.52.3 of i.IMX6 Reference Manual:
Although this PLL does have a DIV_SELECT register field, it is intended that this PLL
will only be run at the default frequency of 528 MHz.
We have specific EMI issues with our i.MX6 board and want to try to switch PLL_SYS to 480 MHz anyway. How can this be done? We tried spread spectrum feature but it brings no relief since the third harmonic of spread clock gets into the sensitive area.