Merge remote-tracking branch 'remotes/sstabellini/xen-140507-2' into staging

* remotes/sstabellini/xen-140507-2:
  xen_disk: add discard support
  pass an inclusive address range to xc_domain_pin_memory_cacheattr
  xen: factor out common functions
  xen: move Xen HVM files under hw/i386/xen
  xen: move Xen PV machine files to hw/xenpv
  qemu-xen: free all the pirqs for msi/msix when driver unload
  exec: Limit translation limiting in address_space_translate to xen

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