mem: Adopt a memory namespace for memories

Encapsulate every class inheriting from Abstract or Physical
memories, and the memory controller in a memory namespace.

Change-Id: I228f7e55efc395089e3616ae0a0a6325867bd782
Issued-on: https://gem5.atlassian.net/browse/GEM5-983
Signed-off-by: Daniel R. Carvalho <odanrc@yahoo.com.br>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/47309
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
Maintainer: Jason Lowe-Power <power.jg@gmail.com>
35 files changed