PCI/MSI: Remove the PCI_MSI_IRQ_DOMAIN architecture whitelist

To: Christoph Hellwig <hch@xxxxxxxxxxxxx>, michal.simek@xxxxxxxxxx, helgaas@xxxxxxxxxx
Subject: PCI/MSI: Remove the PCI_MSI_IRQ_DOMAIN architecture whitelist
From: Palmer Dabbelt <palmer@xxxxxxxxxx>
Date: Thu, 17 Oct 2019 11:19:34 -0700
Cc: tony.luck@xxxxxxxxx, fenghua.yu@xxxxxxxxx, heiko.carstens@xxxxxxxxxx, gor@xxxxxxxxxxxxx, borntraeger@xxxxxxxxxx, bhelgaas@xxxxxxxxxx, will@xxxxxxxxxx, Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx>, Palmer Dabbelt <palmer@xxxxxxxxxx>, kstewart@xxxxxxxxxxxxxxxxxxx, pbonzini@xxxxxxxxxx, firoz.khan@xxxxxxxxxx, yamada.masahiro@xxxxxxxxxxxxx, longman@xxxxxxxxxx, mingo@xxxxxxxxxx, peterz@xxxxxxxxxxxxx, linux-ia64@xxxxxxxxxxxxxxx, linux-kernel@xxxxxxxxxxxxxxx, linux-s390@xxxxxxxxxxxxxxx, linux-pci@xxxxxxxxxxxxxxx

This came up in the context of the microblaze port, where a patch was
recently posted to extend the whitelist.

Follow-Ups:
- Re: PCI/MSI: Remove the PCI_MSI_IRQ_DOMAIN architecture whitelist
  - From: Michal Simek
- [PATCH 1/3] ia64: Use the generic msi.h
  - From: Palmer Dabbelt
- [PATCH 3/3] pci: Default to PCI_MSI_IRQ_DOMAIN
  - From: Palmer Dabbelt
- [PATCH 2/3] s390: Use the generic msi.h
  - From: Palmer Dabbelt