tools/power turbostat: Warn on bad ACPI LPIT data

On some systems /sys/devices/system/cpu/cpuidle/low_power_idle_cpu_residency_us
or /sys/devices/system/cpu/cpuidle/low_power_idle_system_residency_us
return a file error because of bad ACPI LPIT data from a misconfigured BIOS.
turbostat interprets this failure as a fatal error and outputs

turbostat: CPU LPI: No data available

If the ACPI LPIT sysfs files return an error output a warning instead of
a fatal error, disable the ACPI LPIT evaluation code, and continue.

Signed-off-by: Prarit Bhargava <[e-mail]>
Signed-off-by: Len Brown <[e-mail]>

tools/power/x86/turbostat/turbostat.c

···
 	fp = fopen_or_die("/sys/devices/system/cpu/cpuidle/low_power_idle_cpu_residency_us", "r");
 
 	retval = fscanf(fp, "%lld", &cpuidle_cur_cpu_lpi_us);
-	if (retval != 1)
-		err(1, "CPU LPI");
+	if (retval != 1) {
+		fprintf(stderr, "Disabling Low Power Idle CPU output\n");
+		BIC_NOT_PRESENT(BIC_CPU_LPI);
+		return -1;
+	}
 
 	fclose(fp);
 
···
 	fp = fopen_or_die("/sys/devices/system/cpu/cpuidle/low_power_idle_system_residency_us", "r");
 
 	retval = fscanf(fp, "%lld", &cpuidle_cur_sys_lpi_us);
-	if (retval != 1)
-		err(1, "SYS LPI");
-
+	if (retval != 1) {
+		fprintf(stderr, "Disabling Low Power Idle System output\n");
+		BIC_NOT_PRESENT(BIC_SYS_LPI);
+		return -1;
+	}
 	fclose(fp);
 
 	return 0;