qemu: increase locked memory limit when a vDPA device is present

qemu: increase locked memory limit when a vDPA device is present

Just like VFIO devices, vDPA devices may need to have all guest memory
pages locked/pinned in order to operate properly. In the case of VFIO
devices (including mdev and NVME, which also use VFIO) libvirt
automatically increases the locked memory limit when one of those
devices is present. This patch modifies that code to also increase the
limit if there are any vDPA devices present.

Resolves: https://bugzilla.redhat.com/1939776
Signed-off-by: Laine Stump <laine@redhat.com>
Reviewed-by: Daniel Henrique Barboza <danielhb413@gmail.com>