selftests/powerpc/pmu: Add interface test for mmcra_ifm field for conditional branch type

The testcase uses "instructions" event to check if the
Instruction filtering mode(IFM) bits are programmed correctly
for conditional branch type. Testcase checks if IFM bits is
programmed correctly to Monitor Mode Control Register A (MMCRA)
via perf interface for ISA v3.1 platform.

Signed-off-by: Kajol Jain <kjain@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220610134113.62991-8-atrajeev@linux.vnet.ibm.com