drm/i915/skl: Factor out computing the DPLL paramaters from the dividers
drm/i915/skl: Factor out computing the DPLL paramaters from the dividers

This part doesn't depend on how we compute the DPLL dividers (p and
p0/p1/p2) and can be reused even if we change the algorithm to do so.
(something that is planned for a followup patch)

Signed-off-by: Damien Lespiau <64bd3cb94f359c1a3ce68dae5e26b40578526277@intel.com>
Reviewed-by: Paulo Zanoni <cc0e04a2103c45cd195651d976f79813d0f66bdf@intel.com>
Signed-off-by: Daniel Vetter <c1b6782c4af8f0673da8923a0702a1832e5940f4@ffwll.ch>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs