Merge remote-tracking branch 'remotes/amit/tags/vser-2.2.0-queue-2' into staging

Fixes a crash when a virtio-serial port is added without a name to it.

# gpg: Signature made Fri 07 Nov 2014 04:58:05 GMT using RSA key ID 854083B6
# gpg: Good signature from "Amit Shah <[email protected]>"
# gpg:                 aka "Amit Shah <[email protected]>"
# gpg:                 aka "Amit Shah <[email protected]>"

* remotes/amit/tags/vser-2.2.0-queue-2:
  virtio-serial: avoid crash when port has no name

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