tools/power turbostat: Repair Segmentation fault when using -i option

Fix regression caused by commit 8e180f3cb6b7510a3bdf14e16ce87c9f5d86f102
(tools/power turbostat: add [-d MSR#][-D MSR#] options to print counter
deltas)

Signed-off-by: Len Brown <len.brown@intel.com>
diff --git a/tools/power/x86/turbostat/turbostat.c b/tools/power/x86/turbostat/turbostat.c
index 2655ae9..9942dee 100644
--- a/tools/power/x86/turbostat/turbostat.c
+++ b/tools/power/x86/turbostat/turbostat.c
@@ -1594,7 +1594,7 @@
 
 	progname = argv[0];
 
-	while ((opt = getopt(argc, argv, "+pPSvisc:sC:m:M:")) != -1) {
+	while ((opt = getopt(argc, argv, "+pPSvi:sc:sC:m:M:")) != -1) {
 		switch (opt) {
 		case 'p':
 			show_core_only++;