base: Add classes that encapsulate a channel address

base: Add classes that encapsulate a channel address

There are cases where the memory system needs to reason about
channel-local addresses. These are currently represented using the
Addr and AddrRange classes. This is not ideal since it doesn't provide
any type safety when working with global addresses and channel-local
addresses. This is particularly problematic when porting existing
components to work in multi-channel configurations.

This changeset introduces the new ChannelAddr and ChannelAddrRange
classes. These classes encapsulate channel-local addresses in a
contiguous address space. These can, for example, be used in a memory
controller to represent a flat address space when calculating timings
or in a sectored cache.

Change-Id: I45d4061ebc8507a10d0a4577b28796dc5ec7a469
Signed-off-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/21600
Reviewed-by: Bobby R. Bruce <bbruce@ucdavis.edu>
Reviewed-by: Daniel Carvalho <odanrc@yahoo.com.br>
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Maintainer: Jason Lowe-Power <jason@lowepower.com>
Tested-by: kokoro <noreply+kokoro@google.com>