[CRYPTO] geode: use consistent IV copy

It is enough if the IV is copied before and after the while loop.
With DM-Crypt is seems not be required to save the IV after encrytion
because a new one is used in the request (dunno about other users).
It is not save to load the IV within while loop and not save afterwards
because we mill end up with the wrong IV if the request goes consists
of more than one page.

Signed-off-by: Sebastian Siewior <sebastian@breakpoint.cc>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>