NFSv4/flexfiles: Cancel I/O if the layout is recalled or revoked

If the layout is recalled or revoked, we want to cancel I/O as quickly
as possible so that we can return the layout.

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