fs/direct-io.c: fix kernel-doc warning

fs/direct-io.c: fix kernel-doc warning

Fix kernel-doc warning in fs/direct-io.c:

  fs/direct-io.c:258: warning: Excess function parameter 'offset' description in 'dio_complete'

Also, don't mark this function as having kernel-doc notation since it is
not exported.

Link: http://lkml.kernel.org/r/97908511-4328-4a56-17fe-f43a1d7aa470@infradead.org
Fixes: 6d544bb4d901 ("dio: centralize completion in dio_complete()")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Zach Brown <zab@zabbo.net>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>