orangefs: stop setting atime on inode dirty

The previous code path was to mark the inode dirty, let
orangefs_inode_dirty set a flag in our private inode, then later during
inode release call orangefs_flush_inode which notices the flag and
writes the atime out.

The code path worked almost identically for mtime, ctime, and mode
except that those flags are set explicitly and not as side effects of
dirty.

Now orangefs_flush_inode is removed.  Marking an inode dirty does not
imply an atime update.  Any place where flags were set before is now
an explicit call to orangefs_inode_setattr.  Since OrangeFS does not
utilize inode writeback, the attribute change should be written out
immediately.

Fixes generic/120.

In namei.c, there are several places where the directory mtime and ctime
are set, but only the mtime is sent to the server.  These don't seem
right, but I've left them as is for now.

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