PCI: apple: Dynamically allocate RID-to_SID bitmap

As we move towards supporting SoCs with varying RID-to-SID mapping
capabilities, turn the static SID tracking bitmap into a dynamically
allocated one. The current allocation size is still the same, but
that's about to change.

Signed-off-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
Tested-by: Janne Grunau <j@jannau.net>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Acked-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Link: https://patch.msgid.link/20250401091713.2765724-7-maz@kernel.org