Force calling BlockRingPoll as DPC may not run.
Force calling BlockRingPoll as DPC may not run.

Signed-off-by: Owen Smith <ff5e3d9c9f82290ce2a1ee2b399fd0e8322eba85@citrix.com>

xenserver/win-xenvbd,xenserver/win-xenvbd,xenserver/win-xenvbd