Fix Typo in VoiceRegResult

When building a voice registration state result, there
was a typo causing the method to try and build a DataRegResult.
This causes a crash if anybody checks voice reg specific fields.

Bug: 153944103
Test: compilation (trivial)
Merged-In: Id0170888537c61ef6e07f01869029d72676d5406
Change-Id: Id0170888537c61ef6e07f01869029d72676d5406
(cherry picked from commit b64c98a3)