powerpc/perf: init pmu from core-book3s

Currenty pmu driver file for each ppc64 generation processor
has a __init call in itself. Refactor the code by moving the
__init call to core-books.c. This also clean's up compat mode
pmu driver registration.

Suggested-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Madhavan Srinivasan <maddy@linux.vnet.ibm.com>
[mpe: Use SPDX tag for license]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/perf/power6-pmu.c

@@ -540,7 +540,7 @@ static struct power_pmu power6_pmu = {
 	.cache_events		= &power6_cache_events,
 };
 
-static int __init init_power6_pmu(void)
+int init_power6_pmu(void)
 {
 	if (!cur_cpu_spec->oprofile_cpu_type ||
 	    strcmp(cur_cpu_spec->oprofile_cpu_type, "ppc64/power6"))
@@ -548,5 +548,3 @@ static int __init init_power6_pmu(void)
 
 	return register_power_pmu(&power6_pmu);
 }
-
-early_initcall(init_power6_pmu);