perf test sample-parsing: Fix branch_stack entry endianness check

perf test sample-parsing: Fix branch_stack entry endianness check

Commit 884933ec8bacb2a2 ("perf test sample-parsing: Add endian test for
struct branch_flags") broke the test case 27 (Sample parsing) on s390 on
linux-next tree:

  # perf test -Fv 27
  27: Sample parsing
  --- start ---
  parsing failed for sample_type 0x800
  ---- end ----
  Sample parsing: FAILED!
  #

The cause of the failure is a wrong #define BS_EXPECTED_BE statement in
above commit.  Correct this define and the test case runs fine.

Output After:

  # perf test -Fv 27
  27: Sample parsing                                                  :
  --- start ---
  ---- end ----
  Sample parsing: Ok
  #

Fixes: 884933ec8bacb2 ("perf test sample-parsing: Add endian test for struct branch_flags")
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Tested-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Acked-by: Madhavan Srinivasan <maddy@linux.ibm.com>
CC: Sven Schnelle <svens@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Sumanth Korikkar <sumanthk@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Link: https://lore.kernel.org/r/54077e81-503e-3405-6cb0-6541eb5532cc@linux.ibm.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>