arm, tests: Update config files to more recent kernels and create 64-bit regressions.

This changes the default ARM system to a Versatile Express-like system that supports
2GB of memory and PCI devices and updates the default kernels/file-systems for
AArch64 ARM systems (64-bit) to support up to 32GB of memory and PCI devices. Some
platforms that are no longer supported have been pruned from the configuration files.

In addition a set of 64-bit ARM regressions have been added to the regression system.