Fixup duplicate zero_element and uninit_element definition

The two values are already defined in [simd.syn].

Author: mattkretz

source/numerics.tex

@@ -18686,11 +18686,6 @@
 
 \rSec3[simd.permute.static]{\tcode{simd} static permute}
 
-\begin{itemdecl}
-static constexpr @\exposid{simd-size-type}@ zero_element   = @\impdefx{value of \tcode{simd::zero_element}}@;
-static constexpr @\exposid{simd-size-type}@ uninit_element = @\impdefx{value of \tcode{simd::uninit_element}}@;
-\end{itemdecl}
-
 \begin{itemdecl}
 template<@\exposid{simd-size-type}@ N = @\seebelow@, @\exposconcept{simd-type}@ V, class IdxMap>
 constexpr resize_t<N, V> permute(const V& v, IdxMap&& idxmap);