crypto: pcrypt - Fix user-after-free on module unload

crypto: pcrypt - Fix user-after-free on module unload

commit 07bfd9bdf568a38d9440c607b72342036011f727 upstream.

On module unload of pcrypt we must unregister the crypto algorithms
first and then tear down the padata structure.  As otherwise the
crypto algorithms are still alive and can be used while the padata
structure is being freed.

Fixes: 5068c7a883d1 ("crypto: pcrypt - Add pcrypt crypto...")
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>