mem-cache: Add missing includes in TreePLRU

Add missing includes to TreePLRU files.

Change-Id: Ia1e7b2aa91eec8a30b6dccf513cca37a3058b350
Reviewed-on: https://gem5-review.googlesource.com/c/13477
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Maintainer: Nikos Nikoleris <nikos.nikoleris@arm.com>

mem-cache: Create Tree-PLRU replacement policy

Implementation of a Tree-PLRU replacement policy. It is based on
the assumption that a set associative cache is used.

Change-Id: I74b227e88fd6c93aab5bb2cd0e8730376db28f52
Reviewed-on: https://gem5-review.googlesource.com/c/11106
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Maintainer: Jason Lowe-Power <jason@lowepower.com>