[MLIR][LLVM] Support inlining of LLVM atomic operations.

[definelicht]

Summary

These don't require any special handling, apart checking for unsupported
metadata, which is already implemented.

[definelicht]

Update inlining test.

[gysit]

LGTM!

mlir/lib/Dialect/LLVMIR/IR/LLVMInlining.cpp

if (auto iface = dyn_cast<LLVM::AccessGroupOpInterface>(op)) {
       if (iface.getAccessGroupsOrNull()) {
         LLVM_DEBUG(llvm::dbgs()
                    << "Cannot inline: unhandled access group metadata\n");
         return false;
       }
     }
     // clang-format off
     if (isa<LLVM::AllocaOp,
+            LLVM::AtomicRMWOp,
+            LLVM::AtomicCmpXchgOp,
             LLVM::CallOp,
             LLVM::DbgDeclareOp,
             LLVM::DbgValueOp,
+            LLVM::FenceOp,
+            LLVM::InlineAsmOp,
             LLVM::LifetimeEndOp,
             LLVM::LifetimeStartOp,
             LLVM::LoadOp,
             LLVM::MemcpyOp,
             LLVM::MemmoveOp,
             LLVM::MemsetOp,
             LLVM::StackRestoreOp,
             LLVM::StackSaveOp,