CoreSight TMC-ETR must have the non-secure invasive debug access
enabled for use by self-hosted tracing. Without it, there is no
point in enabling the ETR. So, let us check it in the TMC_AUTHSTATUS
register and fail the probe if it is disabled.

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>
Link: https://lore.kernel.org/r/20190829202842.580-7-mathieu.poirier@linaro.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>