linux-phytec-fsl

MLK-13062 arm: imx: correct PLL2 rate calculation

As i.MX6's PLL2 also support a fractional-N
synthesizer, so we need to consider the NUM
and DENOM's value to get a correct rate, as
fraction may be used in some cases.

Remove round_rate and set_rate for PLL2, as
it is NOT allowed to be changed in kernel
dynamically, otherwise, PFDs and DDR may NOT
work normally, it normally should be changed
in u-boot before DDR is enabled.

Signed-off-by: Anson Huang <Anson.Huang@nxp.com>