[llvm] DAG: Fix chain mismanagement in SoftenFloatRes_FP_EXTEND (PR #74406)

[Matt Arsenault via llvm-commits]

================
@@ -1804,6 +1816,7 @@ bool DAGTypeLegalizer::PromoteIntegerOperand(SDNode *N, unsigned OpNo) {
   case ISD::FP16_TO_FP:
   case ISD::VP_UINT_TO_FP:
   case ISD::UINT_TO_FP:   Res = PromoteIntOp_UINT_TO_FP(N); break;
+  case ISD::STRICT_FP16_TO_FP:
----------------
arsenm wrote:

The non-strict path does the same thing, so I'm just copying that. I don't see much point in renaming it

https://github.com/llvm/llvm-project/pull/74406