perf/x86: Fix PMU detection printout when no PMU is detected

Ran into this cryptic PMU bootup log recently:

[    0.124047] Performance Events:
[    0.125000] smpboot: ...

Turns out we print this if no PMU is detected. Fall back to
the right condition so that the following is printed:

[    0.122381] Performance Events: no PMU driver, software events only.

Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Link: http://lkml.kernel.org/n/tip-u2fwaUffakjp0qkpRfqljgsn@git.kernel.orgSigned-off-by: NIngo Molnar <mingo@kernel.org>

arch/x86/kernel/cpu/perf_event.c

@@ -1506,7 +1506,7 @@ static int __init init_hw_perf_events(void)
 		err = amd_pmu_init();
 		break;
 	default:
-		return 0;
+		err = -ENOTSUPP;
 	}
 	if (err != 0) {
 		pr_cont("no PMU driver, software events only.\n");