[Kernel][Misc] register ops to prevent graph breaks (#6917)

Co-authored-by: Sage Moore <sage@neuralmagic.com>

tests/kernels/test_layernorm.py

@@ -1,6 +1,7 @@
 import pytest
 import torch
 
+from tests.kernels.utils import opcheck
 from vllm.model_executor.layers.layernorm import RMSNorm
 
 DTYPES = [torch.half, torch.bfloat16, torch.float]
@@ -52,3 +53,10 @@ def test_rms_norm(
         torch.testing.assert_close(out[1], ref_out[1], atol=1e-2, rtol=1e-2)
     else:
         torch.testing.assert_close(out, ref_out, atol=1e-2, rtol=1e-2)
+
+    if residual is not None:
+        opcheck(torch.ops._C.fused_add_rms_norm,
+                (x, residual, layer.weight.data, layer.variance_epsilon))
+    else:
+        opcheck(torch.ops._C.rms_norm,
+                (out, x, layer.weight.data, layer.variance_epsilon))