usb: xhci: add endpoint context tracing when an endpoint is added

The configure endpoint command configures all the endpoints that were
flagged to be added or dropped.

To know the content of each of the added endpoints we need to add tracing
to the .add_endpoint() callback, just after initializing all the context
values.

Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>