coresight-tpiu: add CoreSight TPIU driver

This driver manages CoreSight TPIU (Trace Port Interface Unit)
which acts as a sink. TPIU is typically connected to some offchip
hardware hosting a storage buffer.

Signed-off-by: Pratik Patel <pratikp@codeaurora.org>
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>