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

libavfilter/vf_unsharp.c

@@ -22,7 +22,7 @@
  */
 
 /**
- * @file libavfilter/vf_unsharp.c
+ * @file
  * blur / sharpen filter
  *
  * This code is based on: