Fix AVX512FP16 build failure

Eigen/src/Core/arch/AVX512/TypeCasting.h

diff --git a/Eigen/src/Core/arch/AVX512/TypeCasting.h b/Eigen/src/Core/arch/AVX512/TypeCasting.h
index e471684..9508ac6 100644
--- a/Eigen/src/Core/arch/AVX512/TypeCasting.h
+++ b/Eigen/src/Core/arch/AVX512/TypeCasting.h
@@ -42,12 +42,10 @@
 template <>
 struct type_casting_traits<int64_t, double> : vectorized_type_casting_traits<int64_t, double> {};
 
-#ifndef EIGEN_VECTORIZE_AVX512FP16
 template <>
 struct type_casting_traits<half, float> : vectorized_type_casting_traits<half, float> {};
 template <>
 struct type_casting_traits<float, half> : vectorized_type_casting_traits<float, half> {};
-#endif
 
 template <>
 struct type_casting_traits<bfloat16, float> : vectorized_type_casting_traits<bfloat16, float> {};
@@ -249,8 +247,6 @@
   return _mm256_castsi256_si128(a);
 }
 
-#ifndef EIGEN_VECTORIZE_AVX512FP16
-
 template <>
 EIGEN_STRONG_INLINE Packet16f pcast<Packet16h, Packet16f>(const Packet16h& a) {
   return half2float(a);
@@ -261,8 +257,6 @@
   return float2half(a);
 }
 
-#endif
-
 template <>
 EIGEN_STRONG_INLINE Packet16f pcast<Packet16bf, Packet16f>(const Packet16bf& a) {
   return Bf16ToF32(a);