Remove explicit filename from Doxygen @file commands.

Passing an explicit filename to this command is only necessary if the
documentation in the @file block refers to a file different from the
one the block resides in.

Originally committed as revision 22921 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavformat/utils.c

@@ -37,7 +37,7 @@
 #include <assert.h>
 
 /**
- * @file libavformat/utils.c
+ * @file
  * various utility functions for use within FFmpeg
  */