perf docs: Fix man page build wrt perf-arm-coresight.txt

perf build assumes documentation files starting with "perf-" are man
pages but perf-arm-coresight.txt is not a man page:

asciidoc: ERROR: perf-arm-coresight.txt: line 2: malformed manpage title
asciidoc: ERROR: perf-arm-coresight.txt: line 3: name section expected
asciidoc: FAILED: perf-arm-coresight.txt: line 3: section title expected
make[3]: *** [Makefile:266: perf-arm-coresight.xml] Error 1
make[3]: *** Waiting for unfinished jobs....
make[2]: *** [Makefile.perf:895: man] Error 2

Fix by renaming it.

Fixes: dc2e0fb00bb2b24f ("perf test coresight: Add relevant documentation about ARM64 CoreSight testing")
Reported-by: Christian Borntraeger <borntraeger@linux.ibm.com>
Reported-by: Sven Schnelle <svens@linux.ibm.com>
Reviewed-by: Leo Yan <leo.yan@linaro.org>
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Carsten Haitzler <carsten.haitzler@arm.com>
Cc: coresight@lists.linaro.org
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@arm.com>
Cc: Jiri Olsa <jolsa@kernel.org>
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: Peter Zijlstra <peterz@infradead.org>
Cc: Suzuki Poulouse <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/a176a3e1-6ddc-bb63-e41c-15cda8c2d5d2@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>