staging: bcm2835-codec: Correct bytesperline on format changed

The handling of format changed events incorrectly set bytesperline
to the cropped width, which ignored padding and formats with
more than 8bpp.
Fix these.

Reported by: zillevdr <zillevdr@gmx.de>
Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.org>