USB: fix the clear_tt_buffer interface

USB: fix the clear_tt_buffer interface

This patch (as1255) updates the interface for calling
usb_hub_clear_tt_buffer().  Even the name of the function is changed!

When an async URB (i.e., Control or Bulk) going through a high-speed
hub to a non-high-speed device is cancelled or fails, the hub's
Transaction Translator buffer may be left busy still trying to
complete the transaction.  The buffer has to be cleared; that's what
usb_hub_clear_tt_buffer() does.

It isn't safe to send any more URBs to the same endpoint until the TT
buffer is fully clear.  Therefore the HCD needs to be told when the
Clear-TT-Buffer request has finished.  This patch adds a callback
method to struct hc_driver for that purpose, and makes the hub driver
invoke the callback at the proper time.

The patch also changes a couple of names; "hub_tt_kevent" and
"tt.kevent" now look rather antiquated.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>