PPC/S390 [codegen]: Add placeholders instead of no_reg

After https://crrev.com/c/2831872 Baseline and Compare_Baseline
functions need to return proper registers as placeholders.

More details can be found on comment section of this port:
https://crrev.com/c/2830897

Change-Id: I7f91a85f9c85ce1813540b4d525f2dce5faaf279
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2836705Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Reviewed-by: Junliang Yan <junyan@redhat.com>
Commit-Queue: Milad Fa <mfarazma@redhat.com>
Cr-Commit-Position: refs/heads/master@{#74047}

src/codegen/ppc/interface-descriptors-ppc-inl.h

@@ -78,12 +78,12 @@ constexpr Register GrowArrayElementsDescriptor::KeyRegister() { return r6; }
 // static
 constexpr Register BaselineLeaveFrameDescriptor::ParamsSizeRegister() {
   // TODO(v8:11421): Implement on this platform.
-  return no_reg;
+  return r6;
 }
 // static
 constexpr Register BaselineLeaveFrameDescriptor::WeightRegister() {
   // TODO(v8:11421): Implement on this platform.
-  return no_reg;
+  return r7;
 }
 
 // static
@@ -193,7 +193,7 @@ constexpr auto CompareDescriptor::registers() { return RegisterArray(r4, r3); }
 // static
 constexpr auto Compare_BaselineDescriptor::registers() {
   // TODO(v8:11421): Implement on this platform.
-  return RegisterArray();
+  return DefaultRegisterArray();
 }
 
 // static
@@ -202,7 +202,7 @@ constexpr auto BinaryOpDescriptor::registers() { return RegisterArray(r4, r3); }
 // static
 constexpr auto BinaryOp_BaselineDescriptor::registers() {
   // TODO(v8:11421): Implement on this platform.
-  return RegisterArray();
+  return DefaultRegisterArray();
 }
 
 // static

src/codegen/s390/interface-descriptors-s390-inl.h

@@ -78,12 +78,12 @@ constexpr Register GrowArrayElementsDescriptor::KeyRegister() { return r5; }
 // static
 constexpr Register BaselineLeaveFrameDescriptor::ParamsSizeRegister() {
   // TODO(v8:11421): Implement on this platform.
-  return no_reg;
+  return r5;
 }
 // static
 constexpr Register BaselineLeaveFrameDescriptor::WeightRegister() {
   // TODO(v8:11421): Implement on this platform.
-  return no_reg;
+  return r6;
 }
 
 // static
@@ -193,7 +193,7 @@ constexpr auto CompareDescriptor::registers() { return RegisterArray(r3, r2); }
 // static
 constexpr auto Compare_BaselineDescriptor::registers() {
   // TODO(v8:11421): Implement on this platform.
-  return RegisterArray();
+  return DefaultRegisterArray();
 }
 
 // static
@@ -202,7 +202,7 @@ constexpr auto BinaryOpDescriptor::registers() { return RegisterArray(r3, r2); }
 // static
 constexpr auto BinaryOp_BaselineDescriptor::registers() {
   // TODO(v8:11421): Implement on this platform.
-  return RegisterArray();
+  return DefaultRegisterArray();
 }
 
 // static