Convert the zonefs filesystem to use the new mount API.
Tested using the zonefs test suite from:
https://github.com/damien-lemoal/zonefs-toolsSigned-off-by: Bill O'Donnell <bodonnel@redhat.com>
Reviewed-by: Ian Kent <raven@themaw.net>
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>