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

libavutil/timer.h

@@ -1,5 +1,5 @@
 /**
- * @file libavutil/timer.h
+ * @file
  * high precision timer, useful to profile code
  *
  * copyright (c) 2006 Michael Niedermayer <michaelni@gmx.at>