PowerPC 601 Support Retired In Linux 5.10 While Continuing To Bring Up POWER10

The POWER architecture changes have been submitted for the Linux 5.10 kernel. As expected, the PowerPC 601 support is retired as that original 32-bit PowerPC processor from the early 90's.

The PowerPC 601 support is cleared out with Linux 5.10 since it's no longer actively being used on new kernel releases and not part of any default kernel configuration. Given the PowerPC 601 is sufficiently different from later models, it's beneficial to remove the 601 support for reducing the ongoing code/maintenance burden.

Meanwhile, since Linux 5.8 there's been initial POWER10 support building up and that has continued now with Linux 5.10. New POWER10 bits in Linux 5.10 include fixes and additions for detecting the Power ISA v3.1 for POWER10 along with a new idle driver for shallow stop states on these new IBM processors expected to begin shipping in 2021.

The rest of the POWER work for Linux 5.10 includes tweaks to the sched domains code around POWER9/POWER10 hardware topology, other code clean-ups, and an assortment of random fixes.

More details on the POWER work for Linux 5.10 via this pull request.