gitlab-ci: share the image version with the child

gitlab-ci: share the image version with the child

Currently, the image name and version are duplicated in the main
pipeline and the generated, child pipeline.

This is a condition for a future gaffe, so let's use the image from the
main pipeline when generating the child one.

Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>
Cc: Romain Naour <romain.naour@gmail.com>
Cc: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Cc: Arnout Vandecappelle <arnout@mind.be>
Reviewed-by: Romain Naour <romain.naour@gmail.com>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>