Currently the FLL configuration is calculated before it is known which
FLL path the configuration will be applied to. Newer versions of the IP
have differences in the configuration required for each FLL path, which
makes it complicated to calculate the FLL configuration in advance.

This patch simply checks the validity of a requested input and output
frequency before we know which FLL path they will be applied to and
saves the actual calculation of the configuration until we know where
the settings will be applied.
Signed-off-by: Charles Keepax <ckeepax@opensource.wolfsonmicro.com>
Signed-off-by: Mark Brown <broonie@linaro.org>