reg*.c - use a consistent style for (in)equality and assign operators

In some of my older patches I left hugged assignements, and sometimes
I tightly hugged (in)equality operators, and sometime I did not. There
is also some level of inconsistency with some other contributors.

This patch tries to make all such cases consistent, with no hugging.

No actual logic changes should be present in this patch.

Author: demerphq