pmb.qemu: cleanup, refactoring, use consistent hardware, remove vexpress
This is a larger set of various cleanup/refactoring of the QEMU code in pmbootstrap to make QEMU great again.
I have split it into neatly separated commits with explanations (which might be a bit too long), so it's probably better to review the commits rather than the final changes.
This depends on related changes in pmaports: pmaports!1029 (merged)
Closes #1836 (closed)
Edited by Minecrell