drm/amd/display: Fix divide by zero in CURSOR_DST_X_OFFSET calculation

[Why]
Certain situations cause pipes to have a recout of 0, such as when the
dst_rect lies completely outside of a given ODM slice.

[How]
Skip calculation that transforms cursor coordinates to viewport space.

Reviewed-by: Alvin Lee <alvin.lee2@amd.com>
Signed-off-by: Jerry Zuo <jerry.zuo@amd.com>
Signed-off-by: George Shen <george.shen@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>