d/ohmd: Prepare for superceeding the OpenHMD Rift DK2 driver
Downstream, the new Rift driver has complete 6dof support, and fully superceeds OpenHMD in terms of features and usability. This commit is to remind me to re-add this block of code in once the rest of the bits are upstreamed.
Part-of: <https://gitlab.freedesktop.org/monado/monado/-/merge_requests/2428>