oeqa/selftest/cases: add basic barebox tests

oeqa/selftest/cases: add basic barebox tests

This adds basic tests for qemuarm and qemuarm64.

So far, barebox fails to run properly under KVM for the same reasons
u-boot fails to run.

A patch series to address the problem was submitted by Ahmad Fatoum
after debugging the oe-selftest failures for this series:

https://lore.kernel.org/barebox/20241009060511.4121157-1-a.fatoum@pengutronix.de/

For now, simply disable KVM for these tests.

Signed-off-by: Enrico Jorns <ejo@pengutronix.de>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>