mem-ruby: add wakeup_port statement

mem-ruby: add wakeup_port statement

While the wakeUpBuffers/wakeUpAllBuffers check all message buffers,
wakeup_port wakes up only the messages stalled on the specified port
and address. Usage is the same as the stall_and_wait statement, e.g.:

wakeup_port(reqInPort, addr);

Change-Id: I57dc77d574c0016ca55786ce16a73061a1d37f2e
Signed-off-by: Tiago Mück <tiago.muck@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/41155
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
Maintainer: Jason Lowe-Power <power.jg@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>