perf: test: Extend branch stack sampling test for Arm64 BRBE

Add Arm64 BRBE-specific testing to the existing branch stack sampling test.
The test currently passes on the Arm FVP RevC model, but no hardware has
been tested yet.

Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: linux-perf-users@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Co-developed-by: German Gomez <german.gomez@arm.com>
Signed-off-by: German Gomez <german.gomez@arm.com>
Signed-off-by: James Clark <james.clark@arm.com>
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>