gpu: ipu-v3: image-convert: calculate per-tile resize coefficients

Slightly modifying resize coefficients per-tile allows to completely
hide the seams between tiles and to sample the correct input pixels at
the bottom and right edges of the image.

Tiling requires a bilinear interpolator reset at each tile start, which
causes the image to be slightly shifted if the starting pixel should not
have been sampled from an integer pixel position in the source image
according to the full image resizing ratio. To work around this
hardware limitation, calculate per-tile resizing coefficients that make
sure that the correct input pixels are sampled at the tile end.

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Acked-by: Steve Longerbeam <slongerbeam@gmail.com>
Tested-by: Steve Longerbeam <slongerbeam@gmail.com>