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

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

QOM infrastructure fixes and device conversions

* Fixes for -device foo,help

# gpg: Signature made Tue 04 Nov 2014 17:27:41 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: Use qdev_get_device_class() for -device <type>,help
  qdev: Move error printing to the end of qdev_device_help()
  qdev: Create qdev_get_device_class() function

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