imx6q_sabrelite_setup_lava: Set u-boot url to persistent location

Task https://phabricator.collabora.com/T34897

Sabrelite u-boot includes recent critical fixes, so the required image version needs to be specified in the lava setup to be installed.

resolved all threads

approved this merge request

added 2 commits

• 9d17d35b - 1 commit from branch master
• 628c6acd - imx6q_sabrelite_setup_lava: Set u-boot url to persistent location

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enabled an automatic merge when the pipeline for 628c6acd succeeds

merged