drm/i915: extract intel_dvo.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>
Acked-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/1ccf9000ad33b895aea06be41053a5b7bac8459e.1554461791.git.jani.nikula@intel.com

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

@@ -17,6 +17,7 @@ header_test := \
 	intel_csr.h \
 	intel_ddi.h \
 	intel_dp.h \
+	intel_dvo.h \
 	intel_engine_types.h \
 	intel_fbc.h \
 	intel_fbdev.h \

drivers/gpu/drm/i915/intel_display.c

@@ -55,6 +55,7 @@
 #include "intel_dp.h"
 #include "intel_drv.h"
 #include "intel_dsi.h"
+#include "intel_dvo.h"
 #include "intel_fbc.h"
 #include "intel_fbdev.h"
 #include "intel_frontbuffer.h"

drivers/gpu/drm/i915/intel_drv.h

@@ -1874,8 +1874,6 @@ void icl_dsi_init(struct drm_i915_private *dev_priv);
 /* intel_dsi_dcs_backlight.c */
 int intel_dsi_dcs_init_backlight_funcs(struct intel_connector *intel_connector);
 
-/* intel_dvo.c */
-void intel_dvo_init(struct drm_i915_private *dev_priv);
 /* intel_hotplug.c */
 void intel_hpd_poll_init(struct drm_i915_private *dev_priv);
 bool intel_encoder_hotplug(struct intel_encoder *encoder,

drivers/gpu/drm/i915/intel_dvo.c

@@ -36,6 +36,7 @@
 #include "i915_drv.h"
 #include "intel_connector.h"
 #include "intel_drv.h"
+#include "intel_dvo.h"
 #include "intel_panel.h"
 
 #define SIL164_ADDR	0x38

drivers/gpu/drm/i915/intel_dvo.h

+/* SPDX-License-Identifier: MIT */
+/*
+ * Copyright © 2019 Intel Corporation
+ */
+
+#ifndef __INTEL_DVO_H__
+#define __INTEL_DVO_H__
+
+struct drm_i915_private;
+
+void intel_dvo_init(struct drm_i915_private *dev_priv);
+
+#endif /* __INTEL_DVO_H__ */