Avoid spurious boot command list warning

Closes: #181 - skip the misleading warning about boot
commands list for the bootloader method.

Signed-off-by: Neil Williams <neil.williams@linaro.org>
13 jobs for bootmessages in 11 minutes and 28 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  Test
passed #26471
amd64
dispatcher-debian-10

00:03:23

passed #26469
amd64
dispatcher-debian-9

00:03:48

passed #26472
amd64
server-debian-10

00:02:45

passed #26470
amd64
server-debian-9

00:03:18

 
  Analyze
passed #26473
amd64
black

00:00:31

passed #26475
amd64
code_quality

00:00:27

passed #26474
amd64
codestyle

00:00:44

passed #26476
dind amd64 allowed to fail
sast

00:02:45

 
  Build
passed #26479
amd64
amd64/pkg-debian-10

00:01:59

passed #26478
amd64
amd64/pkg-debian-9

00:02:08

passed #26477
amd64
doc

00:02:01

 
  Docker
passed #26480
dind amd64
amd64/lava-dispatcher

00:00:57

passed #26481
dind amd64
amd64/lava-server

00:02:44