vp9: Write height and width to ivf header in SVC example encoder.

Write height and width of top layer to ivf header in SVC.

vpxdec Can't decode it correctly when output is y4m.

Change-Id: I9b2f1d54696611a30e252bdfd182897d191d92b5
diff --git a/examples/vp9_spatial_svc_encoder.c b/examples/vp9_spatial_svc_encoder.c
index 92b3106..a7d9536 100644
--- a/examples/vp9_spatial_svc_encoder.c
+++ b/examples/vp9_spatial_svc_encoder.c
@@ -819,6 +819,8 @@
 #endif
 
   info.codec_fourcc = VP9_FOURCC;
+  info.frame_width = enc_cfg.g_w;
+  info.frame_height = enc_cfg.g_h;
   info.time_base.numerator = enc_cfg.g_timebase.num;
   info.time_base.denominator = enc_cfg.g_timebase.den;