Fix "MSAA" and "SSAA" texts being swapped in enhancements overlay

Previously, when you selected MSAA in the advanced options, you
got MSAA but the enhancements display showed "SSAA".
The opposite happened when you selected SSAA.

src/frontend-common/imgui_overlays.cpp

@@ -270,7 +270,7 @@ void ImGuiManager::DrawEnhancementsOverlay()
   if (g_settings.gpu_multisamples != 1)
   {
     text.AppendFormattedString(" %ux%s", g_settings.gpu_multisamples,
-                               g_settings.gpu_per_sample_shading ? "MSAA" : "SSAA");
+                               g_settings.gpu_per_sample_shading ? "SSAA" : "MSAA");
   }
   if (g_settings.gpu_true_color)
     text.AppendString(" TrueCol");