PCI: Remove PCI_MSI_IRQ_DOMAIN architecture whitelist

PCI: Remove PCI_MSI_IRQ_DOMAIN architecture whitelist

The only apparent reason for the PCI_MSI_IRQ_DOMAIN architecture
whitelist was that it requires msi.h.  Now that msi.h is mandatory in
asm-generic/Kbuild, every arch should have at least the default version,
so remove the whitelist.

Built for all the architectures that play nice with make.cross, but not
boot tested anywhere.

Link: https://lore.kernel.org/r/514e7b040be8ccd69088193aba260da1b89e919c.1571983829.git.michal.simek@xilinx.com
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Waiman Long <longman@redhat.com>