tools/power turbostat: correctly decode of ENERGY_PERFORMANCE_BIAS

When EPB is 0xF, turbosat was incorrectly describing it as "custom"
instead of calling it "powersave":

< cpu0: MSR_IA32_ENERGY_PERF_BIAS: 0x0000000f (custom)
> cpu0: MSR_IA32_ENERGY_PERF_BIAS: 0x0000000f (powersave)
Signed-off-by: NLen Brown <len.brown@intel.com>

tools/power/x86/turbostat/turbostat.c

@@ -1919,7 +1919,7 @@ int print_epb(struct thread_data *t, struct core_data *c, struct pkg_data *p)
 	if (get_msr(cpu, MSR_IA32_ENERGY_PERF_BIAS, &msr))
 		return 0;
 
-	switch (msr & 0x7) {
+	switch (msr & 0xF) {
 	case ENERGY_PERF_BIAS_PERFORMANCE:
 		epb_string = "performance";
 		break;