The GearVR controller component does not appear to be in 4.17P1?
It was fully supported in the 4.16 binary:
4.16:
4.17 the mesh exists in the plugin
however it does not appear in the components list so old projects break when opening.
In favour of a more unified approach to dealing with Motion Controllers in UE4, the Gear VR specific Motion Controller component is no longer needed! You can now use the standard Motion Controller component like you would for any other VR platform. However, in the current version of 4.17 there is a bug with the GearVR Blueprint Component not converting to a Motion Controller Component elegantly causing a crash. Qa ran into this the other day and the Blueprint team already has a fix for it in place that should be out in the next preview build. For now, till the fix hits, try using just the standard Motion Controller component and let me know if that works or not.
Here is an image of what you should see when the changes to the Gear VR Controller go live.
Thanks for the info Sam! 
Does anyone have any advice for accessing motioncontroller trigger? The unified motioncontroller (r) trigger, and axis aren’t working for GearVR in 4.17