remove scaled_mm fallback (#1746)

scaled_mm has supported in pytorch
pytorch/pytorch#140972
This fallback will cause duplicate registration. 
remove this fallback after
pytorch/pytorch#140972 merged

---------

Co-authored-by: Yu, Guangye <[email protected]>
Co-authored-by: Su Tong <[email protected]>

Author: 3 people

src/ATen/native/xpu/XPUFallback.template

@@ -216,7 +216,6 @@ TORCH_LIBRARY_IMPL(aten, XPU, m) {
     "lu_unpack.out",
     "ormqr",
     "ormqr.out",
-    "_scaled_mm",
     "triangular_solve.X",
     "_validate_compressed_sparse_indices",
     "vdot",