For consistency with the WRPLL/LCPLL parameter calculation functions,
split out the SPLL specific logic to its own function.
Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200226203455.23032-10-imre.deak@intel.com