mem-garnet: Fix garnet network interface stats
mem-garnet: Fix garnet network interface stats

Fixing a bug in garnet network interface where flit source delay is
computed using both tick and cycle.

Change-Id: If21a985f371a818611d13e9cd5ce344dbcf5fb2b
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/36416
Reviewed-by: Srikant Bharadwaj <7abd8a1e0eed8fe42789a2587ba3e2bbeb88f55b@amd.com>
Maintainer: Matthew Poremba <f1eb50f3368ce197c52b19f7fdb5aa7a278f15fd@amd.com>
Tested-by: kokoro <2ac7b1f3fa578934c95181d4272be0d3bca00121@google.com>

gem5/gem5,gem5/gem5,gem5/gem5,gem5/gem5,gem5/gem5,gem5/gem5,gem5/gem5