drm/amdgpu: correct MMSCH 1.0 version

MMSCH 1.0 doesn't have major/minor version, only verison.

Signed-off-by: Zhigang Luo <zhigang.luo@amd.com>
Reviewed by Shaoyun.liu <Shaoyun.liu@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>