drm/i915: extract intel_dp_aux_backlight.h from intel_drv.h

It used to be handy that we only had a couple of headers, but over time
intel_drv.h has become unwieldy. Extract declarations to a separate
header file corresponding to the implementation module, clarifying the
modularity of the driver.

Ensure the new header is self-contained, and do so with minimal further
includes, using forward declarations as needed. Include the new header
only where needed, and sort the modified include directives while at it
and as needed.

No functional changes.
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/2e5a386cbdcd361399e94c55d47a12352a5216c7.1556540890.git.jani.nikula@intel.com

drivers/gpu/drm/i915/Makefile.header-test

@@ -22,6 +22,7 @@ header_test := \
 	intel_csr.h \
 	intel_ddi.h \
 	intel_dp.h \
+	intel_dp_aux_backlight.h \
 	intel_dp_link_training.h \
 	intel_dpll_mgr.h \
 	intel_drv.h \

drivers/gpu/drm/i915/intel_dp_aux_backlight.c

@@ -22,6 +22,7 @@
  *
  */
 
+#include "intel_dp_aux_backlight.h"
 #include "intel_drv.h"
 
 static void set_aux_backlight_enable(struct intel_dp *intel_dp, bool enable)

drivers/gpu/drm/i915/intel_dp_aux_backlight.h

+/* SPDX-License-Identifier: MIT */
+/*
+ * Copyright © 2019 Intel Corporation
+ */
+
+#ifndef __INTEL_DP_AUX_BACKLIGHT_H__
+#define __INTEL_DP_AUX_BACKLIGHT_H__
+
+struct intel_connector;
+
+int intel_dp_aux_init_backlight_funcs(struct intel_connector *intel_connector);
+
+#endif /* __INTEL_DP_AUX_BACKLIGHT_H__ */

drivers/gpu/drm/i915/intel_drv.h

@@ -1809,9 +1809,6 @@ int intel_dp_compute_dsc_params(struct intel_dp *intel_dp,
 enum intel_display_power_domain
 intel_dsc_power_domain(const struct intel_crtc_state *crtc_state);
 
-/* intel_dp_aux_backlight.c */
-int intel_dp_aux_init_backlight_funcs(struct intel_connector *intel_connector);
-
 /* intel_dp_mst.c */
 int intel_dp_mst_encoder_init(struct intel_digital_port *intel_dig_port, int conn_id);
 void intel_dp_mst_encoder_cleanup(struct intel_digital_port *intel_dig_port);

drivers/gpu/drm/i915/intel_panel.c

@@ -35,6 +35,7 @@
 #include <linux/pwm.h>
 
 #include "intel_connector.h"
+#include "intel_dp_aux_backlight.h"
 #include "intel_drv.h"
 #include "intel_panel.h"