mem-cache: Make packet const in insertBlock

The packet should not be modified within insertBlock.

Change-Id: If7d2b01fe131f9923194efd155c9e85eeab24d5a
Reviewed-on: https://gem5-review.googlesource.com/10811
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Maintainer: Nikos Nikoleris <nikos.nikoleris@arm.com>
7 files changed