drm/msm/sde: register power domain before smmu init

Register power domain before smmu init to trigger extra probe attempt
for any device that depends on mdp power domain registeration.

This fixed the issue that sde_rotator is not probed during boot.

CRs-Fixed: 2270743
Change-Id: Ia802ee3bf069b8084fc61db3fcbc62dc5934d021
Signed-off-by: Xiaowen Wu <wxiaowen@codeaurora.org>