NFSv4.2: fix CLONE/COPY attrs in presence of delegated attributes

xfstest generic/407 is failing in 2 ways. It detects that after
doing a clone the client does not update it's mtime and it's ctime.
CLONE always sends a GETATTR operation and then calls
nfs_post_op_update_inode() based on the returned attributes.
Because of the delegated attributes the client ignores updating
the mtime. Then also, when delegated attributes are present, for
the change_attr the server replies with the same values as what
the client cached before and thus the generic/407 would flag that.
Instead, make sure we invalidate the blocks attr.

By adding updating delegated attributes in nfs42_copy_dest_done()
both COPY and CLONE would update mtime appropriately.

Fixes: e12912d94137 ("NFSv4: Add support for delegated atime and mtime attributes")
Signed-off-by: Olga Kornievskaia <okorniev@redhat.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>