sparc: Don't do expensive hypervisor PCR write unless necessary.

The hypervisor call is only necessary if hypervisor events are
being requested.

So if we're not tracking hypervisor events, simply do a direct
register write.
Signed-off-by: David S. Miller <davem@davemloft.net>

arch/sparc/kernel/pcr.c

@@ -80,9 +80,12 @@ static void n2_pcr_write(u64 val)
 {
 	unsigned long ret;
 
+	if (val & PCR_N2_HTRACE) {
 		ret = sun4v_niagara2_setperf(HV_N2_PERF_SPARC_CTL, val);
 		if (ret != HV_EOK)
 			write_pcr(val);
+	} else
+		write_pcr(val);
 }
 
 static const struct pcr_ops n2_pcr_ops = {