mem-garnet: Allow empty vnet list for garnet network links

An empty supporting_vnet list is the default and implies that
all vnets are supported. This removes the assert which requires
the list to have a minimum list size of 1.

Change-Id: I6710ba06041164bbd597d98e75374a26a1aa5655
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/34258
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
Maintainer: Jason Lowe-Power <power.jg@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>
diff --git a/src/mem/ruby/network/garnet2.0/NetworkLink.cc b/src/mem/ruby/network/garnet2.0/NetworkLink.cc
index 61baed4..e947781 100644
--- a/src/mem/ruby/network/garnet2.0/NetworkLink.cc
+++ b/src/mem/ruby/network/garnet2.0/NetworkLink.cc
@@ -44,7 +44,6 @@
       link_consumer(nullptr), link_srcQueue(nullptr)
 {
     int num_vnets = (p->supported_vnets).size();
-    assert(num_vnets > 0);
     mVnets.resize(num_vnets);
     bitWidth = p->width;
     for (int i = 0; i < num_vnets; i++) {