vfio/mdev: Removed unused kref

Remove unused kref from the mdev_device structure.

Fixes: 7b96953b ("vfio: Mediated device Core driver")
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: Kirti Wankhede <kwankhede@nvidia.com>
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Signed-off-by: Parav Pandit <parav@mellanox.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

drivers/vfio/mdev/mdev_core.c

@@ -311,7 +311,6 @@ int mdev_device_create(struct kobject *kobj,
 	mutex_unlock(&mdev_list_lock);
 
 	mdev->parent = parent;
-	kref_init(&mdev->ref);
 
 	mdev->dev.parent  = dev;
 	mdev->dev.bus     = &mdev_bus_type;

drivers/vfio/mdev/mdev_private.h

@@ -30,7 +30,6 @@ struct mdev_device {
 	struct mdev_parent *parent;
 	guid_t uuid;
 	void *driver_data;
-	struct kref ref;
 	struct list_head next;
 	struct kobject *type_kobj;
 	bool active;