mkimg: Regenerate all the tests for gpt
Recent changes to mkimg has changed the generated GPT images to be more
correct. Use make rebase to regenerate the baseline.
Sponsored by: Netflix
(cherry picked from commit d2abbfede5342b19f3e5994140cdb6622c95ef66)
(cherry picked from commit 524225dde0b5a4f346644670f22fcd11fe13c1f2)
Approved-by: re (cperciva)