drm/amdgpu/vce3: only enable 3 rings on new enough firmware (v2)

Older firmware versions don't support 3 rings.

fixes:
https://bugs.freedesktop.org/show_bug.cgi?id=98016



v2: use define for fw version

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