drm/amd/pm/smu13: BACO is supported when it's in BACO state

This leverages the logic in smu11. No need to talk to SMU to
check BACO enablement as it's in BACO state already.

Signed-off-by: Guchun Chen <guchun.chen@amd.com>
Reviewed-by: Kenneth Feng <kenneth.feng@amd.com>
Reviewed-by: Lijo Lazar <lijo.lazar@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>