drm/i915: Use intel_ types in intel_modeset_clear_plls()

Pass around intel_atomic_state rather than drm_atomic_state.
This avoids some extra casts and annoing aliasing variables.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190517193132.8140-4-ville.syrjala@linux.intel.com


Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>