SUNRPC: Ensure that we free the rpc_task after cleanups are done

SUNRPC: Ensure that we free the rpc_task after cleanups are done

commit c6567ed1402c55e19b012e66a8398baec2a726f3 upstream.

This patch ensures that we free the rpc_task after the cleanup callbacks
are done in order to avoid a deadlock problem that can be triggered if
the callback needs to wait for another workqueue item to complete.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Cc: Weston Andros Adamson <dros@netapp.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Bruce Fields <bfields@fieldses.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>