usb: xhci: add debugfs support for ep with stream

usb: xhci: add debugfs support for ep with stream

To show the trb ring of streams, use the exsiting ring files of bulk ep
to show trb ring of one specific stream ID, which stream ID's trb ring
will be shown, is controlled by a new debugfs file stream_id, this is to
avoid to create a large number of dir for every allocate stream IDs,
another debugfs file stream_context_array is created to show all the
allocated stream context array entries.

Signed-off-by: Li Jun <jun.li@nxp.com>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Link: https://lore.kernel.org/r/20200918131752.16488-11-mathias.nyman@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>