Add support for generation of interrupts from the device directly to the
VM to the VCPU thus avoiding the overhead on the host CPU.

When supported, the driver will attempt to allocate vectors for each
data virtqueue. If a vector for a virtqueue cannot be provided it will
use the QP mode where notifications go through the driver.

In addition, we add a shutdown callback to make sure allocated
interrupts are released in case of shutdown to allow clean shutdown.
Signed-off-by: Eli Cohen <elic@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>
Message-Id: <20230607190007.290505-1-dtatulea@nvidia.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>