S390: fix byte count when pushing/popping doubles

`NumRegs` runs a `population count` and must be used with
a `RegList` and not with a regular integer value.

kCallerSavedDoubles is a regular integer and should be used as is.

Change-Id: Id9535134ad4ea02bebed9b506012084d93acc2c2
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2965159Reviewed-by: Junliang Yan <junyan@redhat.com>
Commit-Queue: Milad Fa <mfarazma@redhat.com>
Cr-Commit-Position: refs/heads/master@{#75213}

src/codegen/s390/macro-assembler-s390.cc

@@ -283,7 +283,7 @@ int TurboAssembler::RequiredStackSizeForCallerSaved(SaveFPRegsMode fp_mode,
   bytes += NumRegs(list) * kSystemPointerSize;
 
   if (fp_mode == SaveFPRegsMode::kSave) {
-    bytes += NumRegs(kCallerSavedDoubles) * kDoubleSize;
+    bytes += kCallerSavedDoubles * kDoubleSize;
   }
 
   return bytes;
@@ -309,7 +309,7 @@ int TurboAssembler::PushCallerSaved(SaveFPRegsMode fp_mode, Register exclusion1,
 
   if (fp_mode == SaveFPRegsMode::kSave) {
     MultiPushDoubles(kCallerSavedDoubles);
-    bytes += NumRegs(kCallerSavedDoubles) * kDoubleSize;
+    bytes += kCallerSavedDoubles * kDoubleSize;
   }
 
   return bytes;
@@ -320,7 +320,7 @@ int TurboAssembler::PopCallerSaved(SaveFPRegsMode fp_mode, Register exclusion1,
   int bytes = 0;
   if (fp_mode == SaveFPRegsMode::kSave) {
     MultiPopDoubles(kCallerSavedDoubles);
-    bytes += NumRegs(kCallerSavedDoubles) * kDoubleSize;
+    bytes += kCallerSavedDoubles * kDoubleSize;
   }
 
   RegList exclusions = 0;