Remove VertexLoaderBase::IsInitialized

It is no longer relevant for the current set of loaders after 7030542546.  If it becomes relevant again, a static function named IsUsable or IsCompatibleWithCurrentMachine or something would be a better approach.

Source/Core/VideoCommon/VertexLoaderARM64.cpp

@@ -53,9 +53,6 @@ alignas(16) static const float scale_factors[] = {
 VertexLoaderARM64::VertexLoaderARM64(const TVtxDesc& vtx_desc, const VAT& vtx_att)
     : VertexLoaderBase(vtx_desc, vtx_att), m_float_emit(this)
 {
-  if (!IsInitialized())
-    return;
-
   AllocCodeSpace(4096);
   ClearCodeSpace();
   GenerateVertexLoader();