powerpc/perf: Cleanup of PM_BR_CMPL vs. PM_BRU_CMPL in Power9 event list

Fixes: 34922527

 ("powerpc/perf: Add power9 event list macros for generic and cache events")
Signed-off-by: Madhavan Srinivasan <maddy@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>