drm/amdgpu: correct mmBIF_SDMA4_DOORBELL_RANGE address for aldebaran

On aldebaran, mmBIF_SDMA4_DOORBELL_RANGE isn't right next to
mmBIF_SDMA3_DOORBELL_RANGE.

Signed-off-by: Le Ma <le.ma@amd.com>
Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Acked-by: Evan Quan <evan.quan@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>