When performing a transformation the hardware is given result
descriptors to save the result data. Those result descriptors are
batched using a 'first' and a 'last' bit. There are cases were more
descriptors than needed are given to the engine, leading to the engine
only using some of them, and not setting the last bit on the last
descriptor we gave. This causes issues were the driver and the hardware
aren't in sync anymore about the number of result descriptors given (as
the driver do not give a pool of descriptor to use for any
transformation, but a pool of descriptors to use *per* transformation).

This patch fixes it by attaching the number of given result descriptors
to the requests, and by using this number instead of the 'last' bit
found on the descriptors to process them.
Signed-off-by: Antoine Tenart <antoine.tenart@bootlin.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>