selftests/powerpc/pmu: Add selftest for group constraint check when using same PMC

Testcase for group constraint check when using events with same PMC.
Multiple events in a group asking for same PMC should fail. Testcase
uses "0x22C040" on PMC2 as leader and also subling which is expected to
fail. Using PMC1 for sibling event should pass the test.

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/20220610134113.62991-20-atrajeev@linux.vnet.ibm.com