drm/crtc-helper: Remove most include statements from drm_crtc_helper.h

Remove most include statements from crm_crtc_helper.h and forward-
declare the contained types in drm_crtc_helper.h. Only keep <linux/types.h>
for the definition of 'bool'.
Suggested-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
Acked-by: Jani Nikula <jani.nikula@intel.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230116131235.18917-23-tzimmermann@suse.de

include/drm/drm_crtc_helper.h

@@ -33,13 +33,17 @@
 #ifndef __DRM_CRTC_HELPER_H__
 #define __DRM_CRTC_HELPER_H__
 
-#include <linux/spinlock.h>
 #include <linux/types.h>
-#include <linux/idr.h>
 
-#include <drm/drm_crtc.h>
-#include <drm/drm_modeset_helper_vtables.h>
-#include <drm/drm_modeset_helper.h>
+struct drm_atomic_state;
+struct drm_connector;
+struct drm_crtc;
+struct drm_device;
+struct drm_display_mode;
+struct drm_encoder;
+struct drm_framebuffer;
+struct drm_mode_set;
+struct drm_modeset_acquire_ctx;
 
 void drm_helper_disable_unused_functions(struct drm_device *dev);
 int drm_crtc_helper_set_config(struct drm_mode_set *set,