coresight-etm4x: Adding CoreSight ETM4x driver

This driver manages the CoreSight ETMv4 (Embedded Trace Macrocell) IP block
to support HW assisted tracing on ARMv7 and ARMv8 architectures.

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