Revert "[AMDGPU] Add verification for amdgcn.init.exec.from.input (#128172)"

This reverts commit cafad2b.

Author: ro-i

llvm/lib/IR/Verifier.cpp

@@ -6371,14 +6371,6 @@ void Verifier::visitIntrinsicCall(Intrinsic::ID ID, CallBase &Call) {
           "llvm.amdgcn.cs.chain must be followed by unreachable", &Call);
     break;
   }
-  case Intrinsic::amdgcn_init_exec_from_input: {
-    const Argument *Arg = dyn_cast<Argument>(Call.getOperand(0));
-    Check(Arg && Arg->hasInRegAttr(),
-          "only inreg arguments to the parent function are valid as inputs to "
-          "this intrinsic",
-          &Call);
-    break;
-  }
   case Intrinsic::amdgcn_set_inactive_chain_arg: {
     auto CallerCC = Call.getCaller()->getCallingConv();
     switch (CallerCC) {