Merge remote-tracking branch 'remotes/afaerber/tags/qom-devices-for-peter' into staging

QOM infrastructure fixes and device conversions

* Conversion of cadence_uart to QOM realize
* qom-tree QMP script
* qom-list and qom-set HMP commands to match their QMP counterparts
* Basic qom-tree HMP command
* Cleanups for /machine QOM composition tree

# gpg: Signature made Tue Mar 17 15:02:57 2015 GMT using RSA key ID 3E7E013F
# gpg: Good signature from "Andreas Färber <[email protected]>"
# gpg:                 aka "Andreas Färber <[email protected]>"

* remotes/afaerber/tags/qom-devices-for-peter:
  qdev: Move owner-less IRQs to /machine/unattached
  memory: Move owner-less MemoryRegions to /machine/unattached
  qom: Implement info qom-tree HMP command
  qom: Implement qom-set HMP command
  qom: Implement qom-list HMP command
  scripts: Add qom-tree script
  cadence_uart: Convert to QOM realize()

Signed-off-by: Peter Maydell <[email protected]>