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.

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>