[rock-dkms-bin] DRM_VER does not provide a default OS name

[acxz]

This comment is a continuation of #244 and follows the patch we have for the package.

Upstream issue: ROCm/amdgpu#94

[tpkessler]

Relevant upstream issue ROCm/ROCm-OpenCL-Runtime#122

[acxz]

I am closing this issue as rock-dkms-bin is slated to be deleted.