Deleted extra namespace

Eigen/src/Core/arch/CUDA/TypeCasting.h

diff --git a/Eigen/src/Core/arch/CUDA/TypeCasting.h b/Eigen/src/Core/arch/CUDA/TypeCasting.h
index 6f1e5e6..2944f1b 100644
--- a/Eigen/src/Core/arch/CUDA/TypeCasting.h
+++ b/Eigen/src/Core/arch/CUDA/TypeCasting.h
@@ -130,9 +130,6 @@
 
 #elif defined(EIGEN_VECTORIZE_SSE) && (!EIGEN_ARCH_x86_64) && (!EIGEN_COMP_MSVC)
 
-namespace Eigen {
-namespace internal {
-
 template <>
 struct type_casting_traits<Eigen::half, float> {
   enum {