kconfig: Activate IOMMUFD for s390x machines

Signed-off-by: Cédric Le Goater <clg@redhat.com>
Signed-off-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
Reviewed-by: Matthew Rosato <mjrosato@linux.ibm.com>
Reviewed-by: Eric Farman <farman@linux.ibm.com>
Tested-by: Nicolin Chen <nicolinc@nvidia.com>
Signed-off-by: Cédric Le Goater <clg@redhat.com>

hw/s390x/Kconfig

@@ -6,6 +6,7 @@ config S390_CCW_VIRTIO
     imply VFIO_CCW
     imply WDT_DIAG288
     imply PCIE_DEVICES
+    imply IOMMUFD
     select PCI_EXPRESS
     select S390_FLIC
     select S390_FLIC_KVM if KVM