PPC/s390: Remove the Dummy interface descriptor

Port 4ae5a813

Original Commit Message:

    Having it around is an invitation to use it in new places. This CL
    removes the generic Dummy descriptor and replaces it by other existing
    descriptors if possible, and defines specialized dummies otherwise.

    In the future, every builtin should have a real descriptor. Especially
    new ASM builtins should define descriptors and use them in their
    implementation (use Descriptor::FooRegister() instead of documenting
    the calling convention as comments).

R=jgruber@chromium.org, joransiu@ca.ibm.com, junyan@redhat.com, midawson@redhat.com
BUG=
LOG=N

Change-Id: Ied285739f8ab017f17341c9c3bbbb1217be947e2
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3594539Reviewed-by: Junliang Yan <junyan@redhat.com>
Commit-Queue: Milad Farazmand <mfarazma@redhat.com>
Cr-Commit-Position: refs/heads/main@{#80034}

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

@@ -233,8 +233,7 @@ constexpr auto ConstructStubDescriptor::registers() {
   // r3 : number of arguments
   // r4 : the target to call
   // r6 : the new target
-  // r5 : allocation site or undefined
-  return RegisterArray(r4, r6, r3, r5);
+  return RegisterArray(r4, r6, r3);
 }
 
 // static

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

@@ -233,8 +233,7 @@ constexpr auto ConstructStubDescriptor::registers() {
   // r2 : number of arguments
   // r3 : the target to call
   // r5 : the new target
-  // r4 : allocation site or undefined
-  return RegisterArray(r3, r5, r2, r4);
+  return RegisterArray(r3, r5, r2);
 }
 
 // static