Fix config of number of temporal layers

Needed to produce correct VideoLayersAllocation extension for
scalability mode L1T2. The value in the `spatialLayers` array
is used on this line:
https://source.chromium.org/chromium/chromium/src/+/main:third_party/webrtc/video/video_stream_encoder.cc;drc=c374d11fac252535ccba15975568b1f6552c117e;l=320

Bug: webrtc:11607
Change-Id: I3bcfe738627e0af6f203a9b0f6e5323492e68987
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/267621
Reviewed-by: Danil Chapovalov <danilchap@webrtc.org>
Reviewed-by: Erik Språng <sprang@webrtc.org>
Commit-Queue: Niels Moller <nisse@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#37414}
diff --git a/modules/video_coding/video_codec_initializer.cc b/modules/video_coding/video_codec_initializer.cc
index cece073..e1885d7 100644
--- a/modules/video_coding/video_codec_initializer.cc
+++ b/modules/video_coding/video_codec_initializer.cc
@@ -170,7 +170,9 @@
   video_codec.spatialLayers[0].height = video_codec.height;
   video_codec.spatialLayers[0].maxFramerate = max_framerate;
   video_codec.spatialLayers[0].numberOfTemporalLayers =
-      streams[0].num_temporal_layers.value_or(1);
+      streams[0].scalability_mode.has_value()
+          ? ScalabilityModeToNumTemporalLayers(*streams[0].scalability_mode)
+          : streams[0].num_temporal_layers.value_or(1);
 
   // Set codec specific options
   if (config.encoder_specific_settings)