Fix stucked ovmf-vars-generator

Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2111567
Brew: https://brewweb.engineering.redhat.com/brew/taskinfo?taskID=46795538

qemu-kvm-7.0.0-8.el9 introduced warning for deprecated cpus. This change breaks ovmf-vars-generator handling as it does not properly detect end of qemu-kvm run and becomes stucked forever. This is blocker for any EDK2 build.

We are planning to replace qemu-ovmf-secureboot with virt-firmware in 9.2 so instead of proper and complex fix of the ovmf-vars-generator logic we are just adding -cpu max parameter to qemu-kvm call that is sufficient to keep qemu-kvm behavior before the depreceation warning was added.

As we use qemu-ovmf-secureboot as submodule in EDK2 source git we need to switch it to regular directory as we can't wait for proper update in upstream repository.

Signed-off-by: Miroslav Rezanina mrezanin@redhat.com