vfio: Export vfio device get and put registration helpers

These helpers are useful for managing additional references taken
on the device from other associated VFIO modules.

Original-patch-by: Jason Gunthorpe <[e-mail]>
Signed-off-by: Vivek Kasireddy <[e-mail]>
Reviewed-by: Kevin Tian <[e-mail]>
Tested-by: Alex Mastro <[e-mail]>
Tested-by: Nicolin Chen <[e-mail]>
Signed-off-by: Leon Romanovsky <[e-mail]>
Acked-by: Ankit Agrawal <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Alex Williamson <[e-mail]>

drivers/vfio/vfio_main.c

···
 	if (refcount_dec_and_test(&device->refcount))
 		complete(&device->comp);
 }
+EXPORT_SYMBOL_GPL(vfio_device_put_registration);
 
 bool vfio_device_try_get_registration(struct vfio_device *device)
 {
 	return refcount_inc_not_zero(&device->refcount);
 }
+EXPORT_SYMBOL_GPL(vfio_device_try_get_registration);
 
 /*
  * VFIO driver API

include/linux/vfio.h

···
 int vfio_register_group_dev(struct vfio_device *device);
 int vfio_register_emulated_iommu_dev(struct vfio_device *device);
 void vfio_unregister_group_dev(struct vfio_device *device);
+bool vfio_device_try_get_registration(struct vfio_device *device);
+void vfio_device_put_registration(struct vfio_device *device);
 
 int vfio_assign_device_set(struct vfio_device *device, void *set_id);
 unsigned int vfio_device_set_open_count(struct vfio_device_set *dev_set);