Merge remote-tracking branch 'remotes/mst/tags/for_upstream' into staging

pc, virtio bugfixes for 2.3

Several bugfixes, nothing stands out especially.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
# gpg: Signature made Wed Mar 25 12:42:10 2015 GMT using RSA key ID D28D5469
# gpg: Good signature from "Michael S. Tsirkin <mst@kernel.org>"
# gpg:                 aka "Michael S. Tsirkin <mst@redhat.com>"

* remotes/mst/tags/for_upstream:
  virtio-net: validate backend queue numbers against bus limitation
  virtio-serial: fix virtio config size
  acpi: Add missing GCC_FMT_ATTR to local function

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