ruby: Fixed a deadlock when restoring a checkpoint with garnet

ruby: Fixed a deadlock when restoring a checkpoint with garnet
This patch fixes a problem where in Garnet, the enqueue time in the
VCallocator and the SWallocator which is of type Cycles was being stored
inside a variable with int type.

This lead to a known problem restoring checkpoints with garnet & the fixed
pipeline enabled. That value was really big and didn't fit in the variable
overflowing it, therefore some conditions on the VC allocation stage & the
SW allocation stage were not met and the packets didn't advance through the
network, leading to a deadlock panic right after the checkpoint was restored.

Committed by: Nilay Vaish <nilay@cs.wisc.edu>