drm/amdgpu: update macro for maximum jpeg rings

Update the macro to accomdate more rings.

Signed-off-by: Sathishkumar S <sathishkumar.sundararaju@amd.com>
Acked-by: Leo Liu <leo.liu@amd.com>
Reviewed-by: Sonny Jiang <sonjiang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>