Merge remote-tracking branch 'remotes/kraxel/tags/pull-usb-20150218-1' into staging

Merge remote-tracking branch 'remotes/kraxel/tags/pull-usb-20150218-1' into staging

usb: error handling fixes from Markus, make sysbus ehci arm-only.

# gpg: Signature made Wed Feb 18 09:54:13 2015 GMT using RSA key ID D3E87138
# 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>"

* remotes/kraxel/tags/pull-usb-20150218-1:
  Make sysbus EHCI devices ARM only by default
  PPC: Don't use legacy -usbdevice support for setting up board
  r2d: Don't use legacy -usbdevice support for setting up board
  usb: Change usb_create_simple() to abort on failure
  usb: Suppress bogus error when automatic usb-hub creation fails
  usb: Do not prefix error_setg() messages with "Error: "
  usb: Improve -usbdevice error reporting a bit
  usb: usb_create() can't fail, drop useless error handling

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