cpu: Add a pointer to a generic Nop StaticInst.

This can be used whenever generic code needs a filler instruction that
doesn't do anything.

Change-Id: Ib245d3e880a951e229eb315a09ecc7c47e6ae00f
Reviewed-on: https://gem5-review.googlesource.com/6823
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>
2 files changed