gpu: ipu-v3: image-convert: move tile burst alignment out of loop

gpu: ipu-v3: image-convert: move tile burst alignment out of loop

Burst aligned input and output width can be calculated once per column,
instead of repeatedly for each tile in the column. The same goes for
input and output height per row. Also don't round up the same values
repeatedly.

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>