linux: Reserve direct mmio in mmio allocator
linux: Reserve direct mmio in mmio allocator

Direct mmio range couldn't be assigned to any device, so this commit
exclude them from mmio allocator before build_vm().

BUG=None
TEST=tools/presubimt and boot manatee

Change-Id: I71414de1d44545e2c490ce75f5ced5545752858f
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/crosvm/+/3605163
Reviewed-by: Daniel Verkamp <72bc170b46ec491f7bdd4359a1c0bfed274de40c@chromium.org>
Tested-by: kokoro <2ac7b1f3fa578934c95181d4272be0d3bca00121@google.com>
Commit-Queue: Daniel Verkamp <72bc170b46ec491f7bdd4359a1c0bfed274de40c@chromium.org>

google/crosvm,google/crosvm,google/crosvm,google/crosvm