drm/amdgpu: According hardware design revert vce and uvd doorbell assignment

Now uvd doorbell is from 0xf8-0xfb and vce doorbell is from 0xfc-0xff

Signed-off-by: Frank Min <Frank.Min@amd.com>
Signed-off-by: Xiangliang.Yu <Xiangliang.Yu@amd.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>