cpu,arch: Eliminate the ThreadContext::nextInstAddr method.

This is no longer used.

Change-Id: I0ec170fb3b450430bbeff0a3c37bcdafe70c92b0
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/52053
Tested-by: kokoro <noreply+kokoro@google.com>
Maintainer: Gabe Black <gabe.black@gmail.com>
Reviewed-by: Daniel Carvalho <odanrc@yahoo.com.br>
12 files changed