[scripts] Adds return values to license script
Adds return values to annotate-license script. Return values: 0 - default, nothing was changed 1 - reuse lint complains, but files haven't been modified 2 - files have been modified by the script and have to be staged for commit 3 - both 1 and 2
Signed-off-by: Maksims Svecovs maksims.svecovs@arm.com