drm/amd/display: Use oriented source size when checking cursor scaling

dm_check_crtc_cursor() doesn't take into account plane transforms when
calculating plane scaling, this can result in false positives.

For example, if there's an output with resolution 3840x2160 and the
output is rotated 90 degrees, CRTC_W and CRTC_H will be 3840 and 2160,
respectively, but SRC_W and SRC_H will be 2160 and 3840, respectively.

Since the cursor plane usually has a square buffer attached to it, the
dm_check_crtc_cursor() will think that there's a scale factor mismatch
even though there isn't really.

This fixes an issue where kwin fails to use hardware plane transforms.

Changes since version 1:
- s/orientated/oriented/g

Reviewed-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Signed-off-by: Vlad Zahorodnii <vlad.zahorodnii@kde.org>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>