msi: fix MSI vector limit check in msi_set_mask()

msi: fix MSI vector limit check in msi_set_mask()

MSI supports a maximum of PCI_MSI_VECTORS_MAX vectors - from 0 to
PCI_MSI_VECTORS_MAX - 1.

msi_set_mask() was previously using PCI_MSI_VECTORS_MAX as the upper
limit for MSI vectors. Fix the upper limit to PCI_MSI_VECTORS_MAX - 1.

Fixes: Coverity CID 1490141
Fixes: 08cf3dc61199 vfio-user: handle device interrupts
Signed-off-by: Jagannathan Raman <jag.raman@oracle.com>
Message-Id: <20220623153844.7367-1-jag.raman@oracle.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>