usb-serial: wakeup device on input

usb-serial: wakeup device on input

Currently usb-serial devices are unable to send data into guests with
the xhci controller.  Data is copied into the usb-serial's buffer, but
it is not sent into the guest.  Data coming out of the guest works
properly.  usb-serial devices work properly with ehci.

Have usb-serial call usb_wakeup() when receiving data from the chardev.
This seems to notify the xhci controller and fix inbound data flow.

Also add USB_CFG_ATT_WAKEUP to the device's bmAttributes.  This matches
a real FTDI serial adapter's bmAttributes.

Signed-off-by: Jason Andryuk <jandryuk@gmail.com>
Message-id: 20200306140917.26726-1-jandryuk@gmail.com
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>