CI: Reduce aarch64 catchall job matches

The aarch64 catch-all job is getting close to the hard time limit in
Azure for the free tier. Move i.MX9 boards to the i.MX8 job and move
amlogic entirely to its own job. This brings us down from 85 boards to
51 boards and so should be safe for a while.

Signed-off-by: Tom Rini <trini@konsulko.com>