[media] atmel-isi: remove dependency of the soc-camera framework

This patch converts the atmel-isi driver from a soc-camera driver to a driver
that is stand-alone.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Acked-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>