systemc: Flesh out the sc_port implementation slightly.

This makes other files compile because it changes the relationship
between constructors,etc., slightly.

Change-Id: I8d9a6e12ec640a82da166fe05c4f5e91f3f608de
Reviewed-on: https://gem5-review.googlesource.com/10840
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Maintainer: Gabe Black <gabeblack@google.com>
2 files changed