Fix return code check

The current code reads:

   if ((ret = vr_fragment_table_init(vrouter) < 0))

The check is performed correctly, but since the "<" comparison takes
precedence, ret is now 1, which confuses the module loader into thinking
everything worked out.

Move the parentheses to fix this issue.

Change-Id: I1278cebbdcebe2aec445d491fa471f6f4ebcc8ba