coresight tmc: Detect support for scatter gather

The SG unit in the TMC has been removed in Coresight SoC-600.
This is however advertised by DEVID:Bit 24 = 0b1. On the
previous generation, the bit is RES0, hence we can rely on the
DEVID to detect the support.

Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Mike Leach <mike.leach@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>