coresight tmc: Add support for Coresight SoC 600 TMC

The coresight SoC 600 supports ETR save-restore which allows us
to restore a trace session by retaining the RRP/RWP/STS.Full values
when the TMC leaves the Disabled state. However, the TMC doesn't
have a scatter-gather unit in built.

Also, TMCs have different PIDs in different configurations (ETF,
ETB & ETR), unlike the previous generation.

While the DEVID exposes some of the features/changes in the TMC,
it doesn't explicitly advertises the new save-restore feature
as described above.

Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>