selftests/powerpc: Update bhrb filter sampling test for multiple branch filters

For PERF_SAMPLE_BRANCH_STACK sample type, different branch_sample_type,
ie branch filters are supported. The testcase "bhrb_filter_map_test"
tests the valid and invalid filter maps in different powerpc platforms.
Update this testcase to include scenario to cover multiple branch
filters at sametime. Since powerpc doesn't support multiple filters at
sametime, expect failure during perf_event_open.

Reported-by: Disha Goel <disgoel@linux.vnet.ibm.com>
Signed-off-by: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
Reviewed-by: Kajol Jain <kjain@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220921145255.20972-3-atrajeev@linux.vnet.ibm.com