Merge remote-tracking branch 'remotes/amit-virtio-rng/tags/rng-for-2.3' into staging

Fixes an init-time check for parameter validity

# gpg: Signature made Mon 05 Jan 2015 08:34:05 GMT using RSA key ID 854083B6
# gpg: Good signature from "Amit Shah <amit@amitshah.net>"
# gpg:                 aka "Amit Shah <amit@kernel.org>"
# gpg:                 aka "Amit Shah <amitshah@gmx.net>"

* remotes/amit-virtio-rng/tags/rng-for-2.3:
  virtio-rng: fix check for period_ms validity

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