coresight: ptm: Adds trace return stack option programming for PTM.

coresight: ptm: Adds trace return stack option programming for PTM.

Adds handling to program the return stack option into PTM hardware if
specified in the perf command line.

If option is not supported by the hardware then it will be ignored.
This allows capture to move between core/ETM combinations that have the
hardware support to those that do not.

Signed-off-by: Mike Leach <mike.leach@linaro.org>
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>