Drivers: hv: balloon: Do not post pressure status if interrupted

commit c5e2254f8d63a6654149aa32ac5f2b7dd66a976d upstream.

When we are posting pressure status, we may get interrupted and handle
the un-balloon operation. In this case just don't post the status as we
know the pressure status is stale.

Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>