Fix compilation with CUDA 11 (#2331)

mlx/backend/cuda/reduce/reduce_ops.cuh

@@ -2,6 +2,8 @@
 
 #pragma once
 
+#include "mlx/backend/cuda/device/atomic_ops.cuh"
+#include "mlx/backend/cuda/device/cast_op.cuh"
 #include "mlx/backend/cuda/device/utils.cuh"
 #include "mlx/backend/cuda/reduce/reduce_utils.cuh"
 
@@ -40,15 +42,15 @@ struct Sum {
   }
 
   __device__ void atomic_update(__nv_bfloat16* x, __nv_bfloat16 y) {
-    atomicAdd(x, y);
+    atomic_add(x, y);
   }
 
   __device__ void atomic_update(int* x, int y) {
-    atomicAdd(x, y);
+    atomic_add(x, y);
   }
 
   __device__ void atomic_update(float* x, float y) {
-    atomicAdd(x, y);
+    atomic_add(x, y);
   }
 };
 
@@ -152,7 +154,7 @@ struct ReduceInit<Sum, T> {
     if constexpr (cuda::std::is_same_v<T, cuComplex>) {
       return T{0, 0};
     } else {
-      return typename ReduceResult<Sum, T>::type{0};
+      return cast_to<typename ReduceResult<Sum, T>::type>(0);
     }
   }
 };
@@ -163,7 +165,7 @@ struct ReduceInit<Prod, T> {
     if constexpr (cuda::std::is_same_v<T, cuComplex>) {
       return T{1, 0};
     } else {
-      return typename ReduceResult<Prod, T>::type{1};
+      return cast_to<typename ReduceResult<Prod, T>::type>(1);
     }
   }
 };