kvm tools: ARM: bring generated pci FDT node in-line with kernel binding

Now that the dust has settled on the devicetree bindings for the generic
PCI host controller in the Linux kernel, update the node generated by
kvmtool to match what mainline kernels will expect.

Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
kvm tools: ARM: allow potential relocation of IO port

Whilst our IO port is fixed at CPU physical address 0x0, changing
ARM_IOPORT_AREA should be all that's necessary to move it around in CPU
physical space (it will still be at 0x0 in the bus address space).

This patch ensures we subtract KVM_IOPORT_AREA from the faulting CPU
physical address when calculating the port for kvm__emulate_io.

Reported-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>