perf cs-etm: Save TRCDEVARCH register

When ETE is present save the TRCDEVARCH register and set a new magic
number. It will be used to configure the decoder in a later commit.

Old versions of perf will not be able to open files with this new magic
number, but old files will still work with newer versions of perf.

Reviewed-by: Leo Yan <leo.yan@linaro.org>
Signed-off-by: James Clark <james.clark@arm.com>
Acked-by: Suzuki Poulouse <suzuki.poulose@arm.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: John Garry <john.garry@huawei.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Mike Leach <mike.leach@linaro.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Will Deacon <will@kernel.org>
Cc: coresight@lists.linaro.org
Cc: linux-arm-kernel@lists.infradead.org
Link: https //lore.kernel.org/r/20210806134109.1182235-5-james.clark@arm.com
[ Addressed some cosmetic suggestions by Suzuki Poulouse ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>