Both PCIe0 and PCIe1 controllers are capable of signalling the MSIs
received from endpoint devices to the CPU using GIC-ITS MSI controller.
Add support for it.

Currently, BDF (0:0.0) and BDF (1:0.0) are enabled and with the
msi-map-mask of 0xff00, all the 32 devices under these two busses can
share the same Device ID.

The GIC-ITS MSI implementation provides an advantage over internal MSI
implementation using Locality-specific Peripheral Interrupts (LPI) that
would allow MSIs to be targeted for each CPU core.

It should be noted that the MSIs for BDF (1:0.0) only works with Device
ID of 0x5980 and 0x5a00. Hence, the IDs are swapped.
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Tested-by: Konrad Dybcio <konrad.dybcio@linaro.org> # Xperia 1 IV (WCN6855)
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20230102105821.28243-4-manivannan.sadhasivam@linaro.org