vfio/container: Modify vfio_get_iommu_type() to use a container fd

The 'container' pointer has no other use than its 'fd' attribute.
Simplify the prototype to ease future changes.

Reviewed-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Tested-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Cédric Le Goater <clg@redhat.com>
diff --git a/hw/vfio/container.c b/hw/vfio/container.c
index dc85a79..589f37b 100644
--- a/hw/vfio/container.c
+++ b/hw/vfio/container.c
@@ -354,7 +354,7 @@
 /*
  * vfio_get_iommu_type - selects the richest iommu_type (v2 first)
  */
-static int vfio_get_iommu_type(VFIOContainer *container,
+static int vfio_get_iommu_type(int container_fd,
                                Error **errp)
 {
     int iommu_types[] = { VFIO_TYPE1v2_IOMMU, VFIO_TYPE1_IOMMU,
@@ -362,7 +362,7 @@
     int i;
 
     for (i = 0; i < ARRAY_SIZE(iommu_types); i++) {
-        if (ioctl(container->fd, VFIO_CHECK_EXTENSION, iommu_types[i])) {
+        if (ioctl(container_fd, VFIO_CHECK_EXTENSION, iommu_types[i])) {
             return iommu_types[i];
         }
     }
@@ -399,7 +399,7 @@
     int iommu_type;
     const VFIOIOMMUClass *vioc;
 
-    iommu_type = vfio_get_iommu_type(container, errp);
+    iommu_type = vfio_get_iommu_type(container->fd, errp);
     if (iommu_type < 0) {
         return false;
     }