Switch firmware vq modify command to be issued via the async API to
allow future parallelization. The new refactored function applies the
modify on a range of vqs and waits for their execution to complete.

For now the command is still used in a serial fashion. A later patch
will switch to modifying multiple vqs in parallel.
Signed-off-by: Dragos Tatulea <dtatulea@nvidia.com>
Reviewed-by: Tariq Toukan <tariqt@nvidia.com>
Message-Id: <20240816090159.1967650-6-dtatulea@nvidia.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Eugenio Pérez <eperezma@redhat.com>
Tested-by: Lei Yang <leiyang@redhat.com>