drm/amdgpu: drop invalid IP revision

This was already fixed and dropped in:
commit baf3f8f3 ("drm/amdgpu: handle SRIOV VCN revision parsing")
commit c40bdfb2 ("drm/amdgpu: fix incorrect VCN revision in SRIOV")
But seems to have been accidently been left around in a merge.

Reviewed-by: Luben Tuikov <luben.tuikov@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>