mem-ruby: functions for connecting sequencer ports
mem-ruby: functions for connecting sequencer ports

Added functions for connecting the sequencer and cpu ports.
Using these functions instead of wiring up the ports directly allow
protocols to provide specialized sequencer implementations. For
instance, connecting the cpu icache_port and dcache_port to
different sequencer ports or to different sequencers.

A follow-up patch will update the configurations to use these
functions.

Change-Id: I2d8db8bbfb05c731c0e549f482a9ab93f341474b
Signed-off-by: Tiago Mück <02f879f33eea3aaf6781160757a59709a6f01bed@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/31417
Reviewed-by: Jason Lowe-Power <92de577f37050ad05b60626d2f17913f40dcb1a2@gmail.com>
Maintainer: Jason Lowe-Power <92de577f37050ad05b60626d2f17913f40dcb1a2@gmail.com>
Tested-by: kokoro <2ac7b1f3fa578934c95181d4272be0d3bca00121@google.com>

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