iommufd: Convert to msi_device_has_isolated_msi()

Trivially use the new API.

Link: https://lore.kernel.org/r/4-v3-3313bb5dd3a3+10f11-secure_msi_jgg@nvidia.com


Tested-by: Matthew Rosato <mjrosato@linux.ibm.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>