NFSv4: Mark the inode change attribute up to date in update_changeattr()

When we update the change attribute, we should also clear the flag that
says it is out of date.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>