gpu: ipu-v3: image-convert: select optimal seam positions

Select seam positions that minimize distortions during seam hiding while
satifying input and output IDMAC, rotator, and image format constraints.

This code looks for aligned output seam positions that minimize the
difference between the fractional corresponding ideal input positions
and the input positions rounded to alignment requirements.

Since now tiles can be sized differently, alignment restrictions of the
complete image can be relaxed in the next step.
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Acked-by: Steve Longerbeam <slongerbeam@gmail.com>
Tested-by: Steve Longerbeam <slongerbeam@gmail.com>