Merge remote-tracking branch 'kraxel/usb.72' into staging

* kraxel/usb.72:
  usb-redir: Don't handle interrupt output packets async
  usb-redir: Split usb_handle_interrupt_data into separate in/out functions
  usb-smartcard-reader: Properly NAK interrupt eps when we've no events
  usb-bt: Return NAK instead of STALL when interrupt ep has no data
  uhci: Fix double unlink
  uhci: Don't allow the guest to set port-enabled when there is no dev connected
  uhci: Add a completions_only flag for async completions

Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>