[design] Reset tree rework to allow NDM reset

[marnovandermaas]

In OpenTitan there is an LC reset and a SYS reset. The LC reset, resets everything besides the debug module and some of the PLIC, while the SYS reset, resets the debug domain.

At the moment in Mocha everything is run off of the SYS reset, so we should introduce an LC reset to allow the non-debug module reset to drive something.