EBB (Event Based Branches) are currently only available on POWER8, so we
should skip them on other CPUs.

I've found that at least one test loops forever on 970MP (cycles_with_freeze_test).
Signed-off-by: NDenis Kirjanov <kda@linux-powerpc.org>
[mpe: Minor change log editing, add skip to cpu_event_vs_ebb_test]
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

The Power8 Performance Monitor Unit (PMU) has a new feature called Event
Based Branches (EBB). This commit adds tests of the kernel API for using
EBBs.
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>