No need to pass the iommufd_ucmd pointer.

Link: https://lore.kernel.org/r/20230327093351.44505-2-yi.l.liu@intel.comSigned-off-by: Yi Liu <yi.l.liu@intel.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Tested-by: Nicolin Chen <nicolinc@nvidia.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>