Drop dmcontrol check before abstract command

[en-sc]

The check was introduced in #324.

AFAIU, after #361 and #383 were merged made the check became obsolete.

IMHO, the check is confusing and redundant, since all the fields in question are W1/WARZ, so it can be dropped.

[rtwfroody]

I agree.

haltreq is WARZ so always reads 0. resumereq and ackhavereset are both W1 which should always read 0.

So there's no point in checking that those bits are 0.

[pdonahue-ventana]

I also agree. This is just a clarification and not a normative change. There is no impact on hardware. Debuggers that do such a check will continue to work but we shouldn't require debuggers to do this pointless check.