mm: fix new kernel-doc warning in filemap.c

Fix new kernel-doc warning in mm/filemap.c:

  Warning(mm/filemap.c:2600): Excess function parameter 'ppos' description in '__generic_file_aio_write'
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/filemap.c

@@ -2581,7 +2581,6 @@ EXPORT_SYMBOL(generic_perform_write);
  * @iocb:	IO state structure (file, offset, etc.)
  * @iov:	vector with data to write
  * @nr_segs:	number of segments in the vector
- * @ppos:	position where to write
  *
  * This function does all the work needed for actually writing data to a
  * file. It does all basic checks, removes SUID from the file, updates