[libc++][NFC] Remove unnecessary unsigned comparison with 0 (#108391)

This fixes a `-Wtype-limits` warning emitted when this file is compiled
with GCC when assertions are enabled.

Author: MitalAshok

libcxx/include/experimental/__simd/vec_ext.h

@@ -40,11 +40,11 @@ struct __simd_storage<_Tp, simd_abi::__vec_ext<_Np>> {
   _Tp __data __attribute__((__vector_size__(std::__bit_ceil((sizeof(_Tp) * _Np)))));
 
   _LIBCPP_HIDE_FROM_ABI _Tp __get(size_t __idx) const noexcept {
-    _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(__idx >= 0 && __idx < _Np, "Index is out of bounds");
+    _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(__idx < _Np, "Index is out of bounds");
     return __data[__idx];
   }
   _LIBCPP_HIDE_FROM_ABI void __set(size_t __idx, _Tp __v) noexcept {
-    _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(__idx >= 0 && __idx < _Np, "Index is out of bounds");
+    _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(__idx < _Np, "Index is out of bounds");
     __data[__idx] = __v;
   }
 };