drm/amd/powerplay: correct the way for checking SMU_FEATURE_BACO_BIT support

Since 'smu_feature_is_enabled(smu, SMU_FEATURE_BACO_BIT)' will always return
false considering the 'smu_system_features_control(smu, false)' disabled
all SMU features.

Signed-off-by: Evan Quan <evan.quan@amd.com>
Reviewed-by: Kenneth Feng <kenneth.feng@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>