Merge remote-tracking branch 'remotes/legoater/tags/pull-ppc-20220118' into staging

ppc 7.0 queue:

* More documentation updates (Leonardo)
* Fixes for the 7448 CPU (Fabiano and Cedric)
* Final removal of 403 CPUs and the .load_state_old handler (Cedric)
* More cleanups of PHB4 models (Daniel and Cedric)

# gpg: Signature made Tue 18 Jan 2022 11:59:16 GMT
# gpg:                using RSA key A0F66548F04895EBFE6B0B6051A343C7CFFBECA1
# gpg: Good signature from "Cédric Le Goater <clg@kaod.org>" [undefined]
# gpg: WARNING: This key is not certified with a trusted signature!
# gpg:          There is no indication that the signature belongs to the owner.
# Primary key fingerprint: A0F6 6548 F048 95EB FE6B  0B60 51A3 43C7 CFFB ECA1

* remotes/legoater/tags/pull-ppc-20220118: (31 commits)
  ppc/pnv: Remove PHB4 version property
  ppc/pnv: Add a 'rp_model' class attribute for the PHB4 PEC
  ppc/pnv: Move root port allocation under pnv_pec_default_phb_realize()
  ppc/pnv: rename pnv_pec_stk_update_map()
  ppc/pnv: remove PnvPhb4PecStack object
  ppc/pnv: make PECs create and realize PHB4s
  ppc/pnv: remove PnvPhb4PecStack::stack_no
  ppc/pnv: move default_phb_realize() to pec_realize()
  ppc/pnv: remove stack pointer from PnvPHB4
  ppc/pnv: reduce stack->stack_no usage
  ppc/pnv: introduce PnvPHB4 'pec' property
  ppc/pnv: move phb_regs_mr to PnvPHB4
  ppc/pnv: move nest_regs_mr to PnvPHB4
  ppc/pnv: change pnv_pec_stk_update_map() to use PnvPHB4
  ppc/pnv: move nest_regs[] to PnvPHB4
  ppc/pnv: move mmbar0/mmbar1 and friends to PnvPHB4
  ppc/pnv: change pnv_phb4_update_regions() to use PnvPHB4
  ppc/pnv: move intbar to PnvPHB4
  ppc/pnv: move phbbar to PnvPHB4
  ppc/pnv: move PCI registers to PnvPHB4
  ...

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>