crypto: padlock-sha - Use init_tfm/exit_tfm interface

This patch switches padlock-sha over to the new init_tfm/exit_tfm
interface as opposed to cra_init/cra_exit.  This way the shash API
can make sure that descsize does not exceed the maximum.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Reviewed-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>