misc: Fix a few accidental transitive includes.

misc: Fix a few accidental transitive includes.

Some files depend on definitions from files that they weren't including
themselves. They were working accidentally by getting those definitions
transitively through other, unrelated headers.

Change-Id: I50c919a4eb6c4484d4ee6b7f4fe02f075132964d
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/36282
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
Maintainer: Jason Lowe-Power <power.jg@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>