VideoLoader: remove VAT_*_FRACBITS

They are used to remove the flush amounts, but as we don't
flush anymore on vertex loader changes (only on native
vertex format right now), this optimization is now unneeded.

This will allow us to hard code the frac factors within the
vertex loaders.

Source/Core/VideoBackends/Software/SWVertexLoader.cpp

@@ -176,7 +176,7 @@ void SWVertexLoader::LoadVertex()
 	// convert the vertex from the gc format to the videocommon (hardware optimized) format
 	u8* old = g_video_buffer_read_ptr;
 	m_CurrentLoader->RunVertices(
-		g_main_cp_state.vtx_attr[m_attributeIndex], m_primitiveType, 1,
+		m_primitiveType, 1,
 		DataReader(g_video_buffer_read_ptr, nullptr), // src
 		DataReader(m_LoadedVertices.data(), m_LoadedVertices.data() + m_LoadedVertices.size()) // dst
 	);