devce-type: Fix meson-g12a-sei510

This patch fix lots of problem found on meson-g12a-sei510
- Fix corruption of uboot commands
- Fix boot action, since issuing just "boot" led to ignore what LAVA
setupped via TFTP
15 jobs for sei-fix in 12 minutes and 40 seconds (queued for 4 seconds)
Status Job ID Name Coverage
  Test
passed #57901
amd64
dispatcher-debian-10

00:03:21

passed #57899
amd64
dispatcher-debian-9

00:03:41

passed #57902
amd64
server-debian-10

00:02:09

passed #57900
amd64
server-debian-9

00:02:33

 
  Analyze
passed #57904
amd64
black

00:00:30

passed #57905
amd64
code_quality

00:00:22

passed #57906
amd64
dockerfiles

00:00:21

passed #57907
amd64
job-schema

00:00:26

passed #57908
amd64
pylint

00:02:19

passed #57903
amd64-dind allowed to fail
sast

00:01:48

 
  Build
passed #57911
amd64
amd64/pkg-debian-10

00:01:21

passed #57910
amd64
amd64/pkg-debian-9

00:01:42

passed #57909
amd64
doc

00:01:18

 
  Docker
passed #57912
amd64-dind
amd64/lava-dispatcher

00:04:34

passed #57913
amd64-dind
amd64/lava-server

00:04:55