drm: rename drm_fops.c to drm_file.c

It's not just file ops, but drm_file stuff in general. This is prep
work to extracting a drm_file.h header in the next patch.

Reviewed-by: Gustavo Padovan <gustavo.padovan@collabora.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170308141257.12119-8-daniel.vetter@ffwll.ch
diff --git a/drivers/gpu/drm/drm_internal.h b/drivers/gpu/drm/drm_internal.h
index f37388c..92ff4b9 100644
--- a/drivers/gpu/drm/drm_internal.h
+++ b/drivers/gpu/drm/drm_internal.h
@@ -24,7 +24,7 @@
 #define DRM_IF_MAJOR 1
 #define DRM_IF_MINOR 4
 
-/* drm_fops.c */
+/* drm_file.c */
 extern struct mutex drm_global_mutex;
 void drm_lastclose(struct drm_device *dev);