drm/amd/pm: remove one unsupported smu function for vangogh

This patch is to remove one unsupported smu function, this function
will set the smu feature mask to disable all smu features in exception.
Because vangogh doesn't support to set the smu feature mask
by driver software, so this function is invalid for vangogh.

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