ruby: Fix initial weight in weighted LRU

ruby: Fix initial weight in weighted LRU

Initial weight was using the timestamp instead of the weight.

Change-Id: I61d3c8424f85fd6856957087c477afda111f8ca7
Reviewed-on: https://gem5-review.googlesource.com/10801
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Reviewed-by: Anthony Gutierrez <anthony.gutierrez@amd.com>
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Maintainer: Anthony Gutierrez <anthony.gutierrez@amd.com>