feat(rpi5): add PCI SMCCC support

BCM2712 changes:
  - support all 3 PCIe RCs / segments.
  - don't check for link up: the RC can now be configured to fabricate
all-ones AXI OKAY responses, so no more Arm SErrors when the link is
down (or other conditions).

Also, limit bus 0 to devfn 0 as accesses beyond that may result in
lock-ups.

Change-Id: Ic64785cd68b22571c6638fc3f771703113bc76f6
Signed-off-by: Mario Bălănică <mariobalanica02@gmail.com>
5 files changed