PPC/s390: [cleanup] combine 3 ResumeGenerator stubs into one

src/s390/interface-descriptors-s390.cc

Index: src/s390/interface-descriptors-s390.cc
diff --git a/src/s390/interface-descriptors-s390.cc b/src/s390/interface-descriptors-s390.cc
index 83c08782d60725fee3abdcb0159fb9bf63b3e363..da0b1d4583ff25d7988569a9ecc9b8915ba3dccc 100644
--- a/src/s390/interface-descriptors-s390.cc
+++ b/src/s390/interface-descriptors-s390.cc
@@ -371,7 +371,8 @@ void ResumeGeneratorDescriptor::InitializePlatformSpecific(
   Register registers[] = {
       r2,  // the value to pass to the generator
       r3,  // the JSGeneratorObject to resume
-      r4   // the resume mode (tagged)
+      r4,  // the resume mode (tagged)
+      r5   // SuspendFlags (tagged)
   };
   data->InitializePlatformSpecific(arraysize(registers), registers);
 }