arch: Stop including unnecessary FP headers.

arch: Stop including unnecessary FP headers.

Nothing is used from them. They're probably there as copy/paste from
other ISAs, or old code that's been replaced. This also gets rid of some
 #if guarded includes which is a nice cleanup.

Change-Id: Icd84300fb7531ec203ce4acbdae1d311e56cc873
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/41353
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
Maintainer: Jason Lowe-Power <power.jg@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>