media: imx: Round line size to 4 bytes

I'm not sure what changed, but now the old path with correct rounding doesn't get taken (imx-media-capture.c), and the broken path gets taken (imx7-media-csi.c).

Is this a result of a devicetree change, where the old media driver got swapped for the new one? Can I assume that the old path never gets called on our hardware?

Does this look upstreamable?

Fixes: #440 (closed)