drm/amd/pp: Allocate ucode bo in request_smu_load_fw

ucode bo is needed by request_smu_load_fw,
the request_smu_load_fw maybe called by gfx/sdma
before smu hw init.
so move amdgpu_ucode_bo_init to request_smu_lowd_fw
from smu hw init.

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>