QOM and device refactorings

* QOM unparenting cleanup
* IRQ conversion to QOM

# gpg: Signature made Tue 01 Jul 2014 04:03:23 BST using RSA key ID 3E7E013F
# gpg: Good signature from "Andreas Färber <afaerber@suse.de>"
# gpg:                 aka "Andreas Färber <afaerber@suse.com>"

* remotes/afaerber/tags/qom-devices-for-2.1:
  irq: Slim conversion of qemu_irq to QOM
  irq: Allocate IRQs individually
  hw: Fix qemu_allocate_irqs() leaks
  sdhci: Fix misuse of qemu_free_irqs()
  qom: Remove parent pointer when unparenting

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