arch,sim: Use _m5opRange in System::allocPhysPages.

This removes the hardcoded assumption that the m5 ops live at the
address they use in x86.

Jira Issue: https://gem5.atlassian.net/browse/GEM5-187

Change-Id: Ia551d7cf5b08f926c7756541c92a2af9bb73b88a
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/23181
Reviewed-by: Gabe Black <gabeblack@google.com>
Maintainer: Gabe Black <gabeblack@google.com>
Tested-by: kokoro <noreply+kokoro@google.com>
3 files changed