drm/amdgpu/amdgpu_vcn: convert to IP version checking

Use IP versions rather than asic_type to differentiate
IP version specific features.

v2: squash in fix for navy flounder and sienna cichlid

Acked-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>