base: AddrRange does not merge single interleaved ranges

base: AddrRange does not merge single interleaved ranges

AddrRange does not attempt to merge interleaved address ranges if it
has only one of the ranges.

This is needed to allow XBars to accept request targeting only one
part of a interleaved address range. A use case for this would be
modeling distributed LLCs in which a XBar is used solely to
encapsulate the snoop filter of a single LLC slice.

Change-Id: If71c9cf1444ee11916611afb51eab3a4f1d93985
Signed-off-by: Tiago Muck <tiago.muck@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/18788
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Maintainer: Jason Lowe-Power <jason@lowepower.com>
Tested-by: kokoro <noreply+kokoro@google.com>