gpu: ipu-v3: image-convert: move tile alignment helpers

Move tile_width_align and tile_height_align up so they
can be used by the tile edge position calculation code.

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