drm/amdgpu: remove error message when loading driver

Forget to check UCODE_ID_STORAGE case and will cause to print error
message when loading driver, correct it.

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