drm/amd/powerplay: avoid using pm_en before it is initialized revised

hwmgr->pm_en is initialized at hwmgr_hw_init.

during amdgpu_device_init, there is amdgpu_asic_reset that calls to
soc15_asic_reset (for V320 usecase, Vega10 asic), in which:
1) soc15_asic_reset_method calls to pp_get_asic_baco_capability (pm_en)
2) soc15_asic_baco_reset calls to pp_set_asic_baco_state (pm_en)

pm_en is used in the above two cases while it has not yet been initialized

So avoid using pm_en in the above two functions for V320 passthrough.

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