orangefs: don't mess with I_DIRTY_TIMES in orangefs_flush

Christoph Hellwig noticed that we were doing some unnecessary
work in orangefs_flush:

  orangefs_flush just writes out data on every close(2) call.  There is
  no need to change anything about the dirty state, especially as
  orangefs doesn't treat I_DIRTY_TIMES special in any way.  The code
  seems to come from partially open coding vfs_fsync.

He sent in a patch with the above commit message and also a
patch that was a reversion of another Orangefs patch I had
sent upstream a while ago. I had to fix his reversion patch
so that it would compile which caused his "don't mess with
I_DIRTY_TIMES" patch to fail to apply. So here I have just
remade his patch and applied it after the fixed reversion patch.

Signed-off-by: Mike Marshall <hubcap@omnibond.com>