pcie_sriov: Remove num_vfs from PCIESriovPF

num_vfs is not migrated so use PCI_SRIOV_CTRL_VFE and PCI_SRIOV_NUM_VF
instead.

Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Message-Id: <20250116-reuse-v20-10-7cb370606368@daynix.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>