n_tracerouter and n_tracesink ldisc additions.

The n_tracerouter and n_tracesink line discpline drivers use the
Linux tty line discpline framework to route trace data coming
from a tty port (say UART for example) to the trace sink line
discipline driver and to another tty port(say USB).  Those
these two line discipline drivers can be used together,
independently from pti.c, they are part of the original
implementation solution of the MIPI P1149.7, compact JTAG, PTI
solution for Intel mobile platforms starting with the
Medfield platform.

Signed-off-by: J Freyensee <james_p_freyensee@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>