apb: implement PCI bus error interrupt map registers

Both OpenBSD and FreeBSD SPARC64 attempt to read the interrupt map from the
hardware and will fail if the correct ino isn't present.

Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Merge remote-tracking branch 'remotes/mcayland/tags/qemu-sparc-signed' into staging

apb: implement PCI bus error interrupt map registers

# gpg: Signature made Tue 09 Sep 2014 06:09:27 BST using RSA key ID AE0F321F
# gpg: Can't check signature: public key not found

* remotes/mcayland/tags/qemu-sparc-signed:
  apb: implement PCI bus error interrupt map registers

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>