PIDL (DCERPC misc): enhance dissector

* Fix -Wunused-function (Set NOEMIT winreg_Data and remove unused function)
* Remove dissector DCERPC misc from DIRTY list

Change-Id: If59b14f8db33354a2d5248e8bc256cadee3ea4bf
Reviewed-on: https://code.wireshark.org/review/4345
Reviewed-by: Alexis La Goutte <alexis.lagoutte@gmail.com>
Reviewed-by: Michael Mann <mmann78@netscape.net>