kvm tools: Fix MSI-X table size set up

kvm tools: Fix MSI-X table size set up

We at most have VIRTIO_PCI_MAX_VQ entries for virt queue,
VIRTIO_PCI_MAX_CONFIG entries for config.

To quote the PCI spec:

    System software reads this field to determine the
    MSI-X Table Size N, which is encoded as N-1.
    For example, a returned value of "00000000011"
    indicates a table size of 4.

So, we should set table size to

    VIRTIO_PCI_MAX_VQ + VIRTIO_PCI_MAX_CONFIG - 1

not

    VIRTIO_PCI_MAX_VQ + VIRTIO_PCI_MAX_CONFIG

Acked-by: Sasha Levin <levinsasha928@gmail.com>
Signed-off-by: Asias He <asias.hejun@gmail.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>