PPC: Fix "Rework CallApi*Stubs".

R=joransiu@ca.ibm.com, jyan@ca.ibm.com, michael_dawson@ca.ibm.com
BUG=

Review URL: https://codereview.chromium.org/1779803004

Cr-Commit-Position: refs/heads/master@{#34642}

src/ppc/code-stubs-ppc.cc

@@ -5644,8 +5644,6 @@ void CallApiCallbackStub::Generate(MacroAssembler* masm) {
   STATIC_ASSERT(FCA::kHolderIndex == 0);
   STATIC_ASSERT(FCA::kArgsLength == 7);
 
-  DCHECK(argc.is_immediate() || r6.is(argc.reg()));
-
   // context save
   __ push(context);
   if (!is_lazy()) {