drm/i915: Move intel_dpll_get_hw_state() into the hsw+ platform specific functions

drm/i915: Move intel_dpll_get_hw_state() into the hsw+ platform specific functions

On icl+ we want to populate both crtc_state.{shared_dpll,dpll_hw_state}
and crtc_state.port_dplls[] during readout, whereas on pre-icl we
want to leave the latter stuff untouched. Rather than adding more ifs
into hsw_get_ddi_port_state() to copy the DPLL hw state around let's
just move the whole dpll readout into hsw_get_ddi_dpll() & co.
Slightly repetitive, but meh.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20201109231239.17002-2-ville.syrjala@linux.intel.com
Reviewed-by: Imre Deak <imre.deak@intel.com>