s390/crypto: Use module-local structures for protected keys

s390/crypto: Use module-local structures for protected keys

The paes module uses only AES related structures and constants of the
pkey module. As pkey also supports protected keys other than AES keys,
the structures and size constants of the pkey module may be
changed. Use module-local structures and size constants for paes to
prevent any unwanted side effect by such a change.

The struct pkey_protkey is used to store the protected key blob
together with its length and type. The structure is only used locally,
it is not required for any pkey API call. So define the module-local
structure struct paes_protkey instead.

While at it, unify the names of struct paes_protkey variables on
stack.

The functionality of the paes module is not affected by this commit.

Reviewed-by: Harald Freudenberger <freude@linux.ibm.com>
Signed-off-by: Holger Dengler <dengler@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>