selftests/powerpc/pmu: Add selftest to check PMC5/6 is excluded from some constraint checks

Events using Performance Monitor Counter 5 (PMC5) and Performance
Monitor Counter 6 (PMC6) should be excluded from constraint check when
scheduled along with group of events. Example, combination of PMC5,
PMC6, and an event with cache bit will succeed to schedule though first
two events doesn't have cache bit set. Testcase use three events, ie,
600f4(cycles), 500fa(instructions), 22C040 with cache bit (dc_ic) set to
test this constraint check.

Signed-off-by: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220610134113.62991-18-atrajeev@linux.vnet.ibm.com