drm/amd/pm: Rename enable_bapm() to notify_ac_dc()

drm/amd/pm: Rename enable_bapm() to notify_ac_dc()

No functional changes, just change the name of this
function pointer to be more generic.

BAPM refers to a specific feature on KV, but other kinds of
ASICs may also need the SMU to be notified on AC/DC changes.

Also remove the argument and use adev->pm.ac_power instead.

Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Timur Kristóf <timur.kristof@gmail.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>