drm/i915: Relocate cnl_get_ddi_pll()

Move cnl_get_ddi_pll() into a better spot from between
icl_get_ddi_pll() and dg1_get_ddi_pll(). Also reorder
the calls to the skl and bxt functions because ocd.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20201109231239.17002-4-ville.syrjala@linux.intel.com


Reviewed-by: Imre Deak <imre.deak@intel.com>