[media] v4l: atmel-isi: Remove unused platform data fields

The emb_crc_sync, mck_hz, asd and asd_sizes platform data fields are
unused, remove them.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Tested-by: Josh Wu <josh.wu@atmel.com>
Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>