drm/i915: Add eDP intermediate frequencies for CHV

"P1273_DPLL_Programming Spreadsheet.xlsm" lists a boatload of
frequencies for eDP. Try to use them all.

For now I've decided not to add hardcoded DPLL dividers for these cases
since chv_find_best_dpll() works just fine.

I've not actually tested any of these since I don't have an eDP 1.4 panel.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Sonika Jindal <sonika.jindal@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>