mem: Delete the now unused Message*Port classes.

This port type is no longer used.

Change-Id: If4abbb774819644bea58fd82e00dfdec8f79b5a6
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/20822
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Gabe Black <gabeblack@google.com>
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Maintainer: Gabe Black <gabeblack@google.com>
Maintainer: Jason Lowe-Power <jason@lowepower.com>
3 files changed