drbd: There might be a resync after unfreezing IO due to no disk [Bugz 332]

When on-no-data-accessible is set to suspend-io, also consider that
a Primary, SyncTarget node losses its connection.

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>