[Flang][OpenMP][MLIR] Fix regression by #146653 by adding address space cast to getRefPtrIfDeclareTarget

The patch introduced changes to add address spaces to a wider array of MLIR/LLVM values, however,
it was missing an address space cast that exists in our downstream implementation that's required
for declare target to work correctly.

Author: agozillon

mlir/lib/Target/LLVMIR/Dialect/OpenMP/OpenMPToLLVMIRTranslation.cpp

@@ -3535,11 +3535,13 @@ static llvm::Value *
 getRefPtrIfDeclareTarget(mlir::Value value,
                          LLVM::ModuleTranslation &moduleTranslation) {
   llvm::OpenMPIRBuilder *ompBuilder = moduleTranslation.getOpenMPBuilder();
+  Operation *op = value.getDefiningOp();
+  if (auto addrCast = llvm::dyn_cast_if_present<LLVM::AddrSpaceCastOp>(op))
+    op = addrCast->getOperand(0).getDefiningOp();
 
   // An easier way to do this may just be to keep track of any pointer
   // references and their mapping to their respective operation
-  if (auto addressOfOp =
-          llvm::dyn_cast_if_present<LLVM::AddressOfOp>(value.getDefiningOp())) {
+  if (auto addressOfOp = llvm::dyn_cast_if_present<LLVM::AddressOfOp>(op)) {
     if (auto gOp = llvm::dyn_cast_or_null<LLVM::GlobalOp>(
             addressOfOp->getParentOfType<mlir::ModuleOp>().lookupSymbol(
                 addressOfOp.getGlobalName()))) {