drm/amdgpu: refine code delete duplicated error handling

in function amdgpu_ucode_init_bo, when failed, it will
set load_type to AMDGPU_FW_LOAD_DIRECT.

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