regtools/qeditor: implement UI code to write registers

The UI now has a "read-only" check box to prevent accidently changes: once
unchecked, the UI can do write to register (only full register writes are
supported for now). If the register supports it, the UI provides SCT writes
as well. The display register panel was moved to its own class to cleanup
things a bit.

Change-Id: I0fc6aab3b351f9080076102ee6fad0037ab5353b
2 files changed