vdpa_sim: remove hard-coded virtq count

vdpa_sim: remove hard-coded virtq count

commit 423248d60d2b655321fc49eca1545f95a1bc9d6c upstream.

Add a new attribute that will define the number of virt queues to be
created for the vdpasim device.

Signed-off-by: Max Gurtovoy <mgurtovoy@nvidia.com>
[sgarzare: replace kmalloc_array() with kcalloc()]
Acked-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
Link: https://lore.kernel.org/r/20201215144256.155342-4-sgarzare@redhat.com
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>