UPSTREAM: coresight: tmc-etr: Add support for CPU-wide trace scenarios

(Upstream commit 8d03cfd16a7283e9e7a5aeb7dc0742ceb66d2d23).

This patch adds support for CPU-wide trace scenarios by making sure that
only the sources monitoring the same process have access to a common sink.
Because the sink is shared between sources, the first source to use the
sink switches it on while the last one does the cleanup.  Any attempt to
modify the HW is overlooked for as long as more than one source is using
a sink.

Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Tested-by: Leo Yan <leo.yan@linaro.org>
Tested-by: Robert Walker <robert.walker@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Bug: 140266694
Change-Id: I7096e7b4d105953242b9eca0ed5b040fc8b1f3bc
Signed-off-by: Yabin Cui <yabinc@google.com>