u-boot: use array instead of sting concatenation

This will make it easier to fix #256

Signed-off-by: Rémi Duraffort <remi.duraffort@linaro.org>
15 jobs for uboot in 13 minutes and 24 seconds (queued for 3 seconds)
latest
Status Job ID Name Coverage
  Test
passed #53426
amd64
dispatcher-debian-10

00:02:48

passed #53424
amd64
dispatcher-debian-9

00:03:10

passed #53427
amd64
server-debian-10

00:02:50

passed #53425
amd64
server-debian-9

00:02:31

 
  Analyze
passed #53429
amd64
black

00:00:45

passed #53431
amd64
code_quality

00:00:27

passed #53430
amd64
codestyle

00:00:42

passed #53433
amd64
job-schema

00:01:16

passed #53432
amd64
pylint

00:02:35

passed #53428
amd64-dind allowed to fail
sast

00:01:49

 
  Build
passed #53436
amd64
amd64/pkg-debian-10

00:01:23

passed #53435
amd64
amd64/pkg-debian-9

00:01:47

passed #53434
amd64
doc

00:02:14

 
  Docker
passed #53437
amd64-dind
amd64/lava-dispatcher

00:05:23

passed #53438
amd64-dind
amd64/lava-server

00:05:10