Clean up qemuarm-efi and qemuarm64-efi defconfigs

!250 (merged) added support for qemuarm EFI machines, but they are currently using general purpose kernel defconfig files. These include the support we need but also a lot of additional features.

Find what configs are actually needed so they can be converted into a cfg and based on the existing qemuarm/qemuarm64 support in linux-meta.