fastmodel: Use all possible address spaces when setting up a bp.

fastmodel: Use all possible address spaces when setting up a bp.

gem5 does not historically distinguish between address spaces when
interacting with gdb, and gdb doesn't really give it any address space
information to work with. To ensure we catch whatever address space
we might be in by the time we get to the interesting address, we'll set
a breakpoint in all possible address spaces simultaneously with the
expectation that we'll hit one of them.

Change-Id: I9f4b93d04914db7a3c42be6236a523d35194afda
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/25268
Tested-by: kokoro <noreply+kokoro@google.com>
Maintainer: Gabe Black <gabeblack@google.com>
Reviewed-by: Chun-Chen TK Hsu <chunchenhsu@google.com>