perf tests: Consolidate test__arch_unwind_sample declaration

There's no reason for making the test__arch_unwind_sample declaration per
arch. Currently that's done 2 different ways either with a declaration in
arch-tests.h or with an arch define. Unify all this with an unconditional
declaration in tests.h.

Signed-off-by: Rob Herring <robh@kernel.org>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: John Garry <john.garry@huawei.com>
Cc: Leo Yan <leo.yan@linaro.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Matt Fleming <matt.fleming@intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will@kernel.org>
Cc: linux-arm-kernel@lists.infradead.org
Cc: masayoshi mizuma <msys.mizuma@gmail.com>
Link: http://lore.kernel.org/lkml/20210513174614.2242210-1-robh@kernel.org


Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>