drm/amd/display: Don't treat wb connector as physical in create_validate_stream_for_sink

drm/amd/display: Don't treat wb connector as physical in create_validate_stream_for_sink

Don't try to operate on a drm_wb_connector as an amdgpu_dm_connector.
While dereferencing aconnector->base will "work" it's wrong and
might lead to unknown bad things. Just... don't.

Reviewed-by: Alex Hung <alex.hung@amd.com>
Signed-off-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Roman Li <roman.li@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>