drm/amdgpu: Don't reallocate ucode bo when suspend

driver don't release the ucode memory when suspend. so don't
need to allocate bo when resume back.

Reviewed-by: Evan Quan <evan.quan@amd.com>
Signed-off-by: Rex Zhu <Rex.Zhu@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>