drm/i915: Pass atomic state to encoder hooks

We're going to want access to the atomic state for iterating
the slave crtcs when enabling the port sync master crtc. Pass
the atomic state all the way down.

The alternative would be yet another encoder hook which we'll
have to call after all the normal modeset stuff is done. Not
really a fan of yet another hook just for this.

Note that during readout state sanitation we are now going
to pass NULL as the atomic state since we don't have one.
We need to change that and then we can also s/crtc_state/crtc/
and s/conn_state/conn/ for the encoder hooks as well.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200313164831.5980-13-ville.syrjala@linux.intel.com
Reviewed-by: José Roberto de Souza <jose.souza@intel.com>

drivers/gpu/drm/i915/display/intel_panel.h

@@ -37,7 +37,8 @@ int intel_panel_setup_backlight(struct drm_connector *connector,
 				enum pipe pipe);
 void intel_panel_enable_backlight(const struct intel_crtc_state *crtc_state,
 				  const struct drm_connector_state *conn_state);
-void intel_panel_update_backlight(struct intel_encoder *encoder,
+void intel_panel_update_backlight(struct intel_atomic_state *state,
+				  struct intel_encoder *encoder,
 				  const struct intel_crtc_state *crtc_state,
 				  const struct drm_connector_state *conn_state);
 void intel_panel_disable_backlight(const struct drm_connector_state *old_conn_state);