[PATCH] io_edgeport locking, flow control, and misc fixes

- Updated to version 2.7.

- Added locking to protect the circular buffer, txCredits, rxBytesAvail,
  and read_in_progress.

- With these locking fixes tests running 8 ports at 115200 bps on
  SMP now runs for hours without problems; before these changes this
  test would cause out of memory errors or oopses within minutes.

- Removed the RELEVANT_IFLAG macro which mistakenly filtered out the
  software flow control stty flags.

- Added support for mark and space parity.

- Added a private read_in_progress flag rather than using (urb->status
  == -EINPROGRESS).

- Low latency is now a module parameter, it is on by default.

- Added edge_tty_recv to pass data to the tty flip buffers.

- Cleared the write_urb pointer after freeing it, to prevent oops on
  failed open.

- Cleared the txfifo.fifo pointer after freeing it, to prevent double
  free on failed open.

- Simplified rounding the baud rate divisor.

- Added some error messages.
Signed-off-by: Al Borchers <alborchers@steinerpoint.com>
Signed-off-by: Greg Kroah-Hartman <greg@kroah.com>