Merge remote-tracking branch 'remotes/kraxel/tags/pull-fixes-20170403-1' into staging

bugfixes: xhci, input-linux and vnc

# gpg: Signature made Mon 03 Apr 2017 11:25:29 BST
# gpg:                using RSA key 0x4CB6D8EED3E87138
# gpg: Good signature from "Gerd Hoffmann (work) <kraxel@redhat.com>"
# gpg:                 aka "Gerd Hoffmann <gerd@kraxel.org>"
# gpg:                 aka "Gerd Hoffmann (private) <kraxel@gmail.com>"
# Primary key fingerprint: A032 8CFF B93A 17A7 9901  FE7D 4CB6 D8EE D3E8 7138

* remotes/kraxel/tags/pull-fixes-20170403-1:
  vnc: allow to connect with add_client when -vnc none
  Fix input-linux reading from device
  xhci: flush dequeue pointer to endpoint context

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