staging: sep: reworked crypto layer

This gets the SEP crypto layer up and running with things like dmcrypt.
It's a fairly big set of changes because it has to rework the whole context
handling system.

[This is picked out of the differences between the upstream driver and
 the staging driver. I'm resolving the differences as a series of updates -AC]

Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>