The presence of the power control method should be determined
via the presence of the method in function 0.  However, some
sbioses only set the appropriate bits in function 1 so use
then to override a missing power control function.
Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Acked-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>