Linux 5.20 compat: blk_cleanup_disk()

As of the Linux 5.20 kernel blk_cleanup_disk() has been removed,
all callers should use put_disk().

Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #13728