PCI: apple: Abstract register offsets via a SoC-specific structure

PCI: apple: Abstract register offsets via a SoC-specific structure

Newer versions of the Apple PCIe block have a bunch of small, but
annoying differences.

In order to embrace this diversity of implementations, move the
currently hardcoded offsets into a hw_info structure. Future SoCs
will provide their own structure describing the applicable offsets.

Signed-off-by: Hector Martin <marcan@marcan.st>
Signed-off-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
[maz: split from original patch to only address T8103]
Signed-off-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Tested-by: Janne Grunau <j@jannau.net>
Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Acked-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Link: https://patch.msgid.link/20250401091713.2765724-13-maz@kernel.org