drm: make drm_internal.h self-contained

Do not require users of drm_internal.h to include other
files just to let it build
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Acked-by: Daniel Vetter <daniel@ffwll.ch>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Maxime Ripard <maxime.ripard@bootlin.com>
Cc: Sean Paul <sean@poorly.run>
Cc: David Airlie <airlied@linux.ie>
Link: https://patchwork.freedesktop.org/patch/msgid/20190526173535.32701-5-sam@ravnborg.org

drivers/gpu/drm/drm_internal.h

@@ -28,8 +28,16 @@
 
 #define DRM_IF_VERSION(maj, min) (maj << 16 | min)
 
-struct drm_prime_file_private;
+struct dentry;
 struct dma_buf;
+struct drm_connector;
+struct drm_crtc;
+struct drm_framebuffer;
+struct drm_gem_object;
+struct drm_master;
+struct drm_minor;
+struct drm_prime_file_private;
+struct drm_printer;
 
 /* drm_file.c */
 extern struct mutex drm_global_mutex;