drm/amd/display: Check scaling ration not viewports params.

In case of roation, width and height in viewport is difference
between viewport and h_active and v_active, while this is not scaling.
The right way is check ratios in scaling data,
to determine it is a scaling case or not.

Signed-off-by: Yongqiang Sun <yongqiang.sun@amd.com>
Reviewed-by: Tony Cheng <Tony.Cheng@amd.com>
Acked-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>