fix: Only do spatial SVC when there are > 1 layers

Bug introduced in I930dced169c9d53f8044d2754a04332138347409. If
svc.number_temporal_layers == 1 and svc.number_spatial_layers == 1, the system
attempt to do spatial SVC. It no longer does that.

Change-Id: Ie6b130a72b1eea40c547c9a64447e40695f811c5
1 file changed