solidrun-imx6.coffee: Update to rocko
solidrun-imx6.coffee: Update to rocko

Changelog-entry: solidrun-imx6.coffee: Update to rocko
Signed-off-by: Sebastian Panceac <db043b2055cb3a47b2eb0b5aebf4e114a8c24a5a@resin.io>

resin-os/resin-fsl-arm