virtio-blk: move config size params to virtio-blk-common

virtio-blk: move config size params to virtio-blk-common

This way we can reuse it for other virtio-blk devices, e.g
vhost-user-blk, which currently does not control its config space size
dynamically.

Signed-off-by: Daniil Tatianin <d-tatianin@yandex-team.ru>
Reviewed-by: Raphael Norwitz <raphael.norwitz@nutanix.com>
Message-Id: <20220906073111.353245-3-d-tatianin@yandex-team.ru>
Reviewed-by: Raphael Norwitz <raphael.norwitz@nutanix.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>