crypto: caam - remove needless ablkcipher key copy

ablkcipher shared descriptors are relatively small, thus there is enough
space for the key to be inlined.
Accordingly, there is no need to copy the key in ctx->key.

Signed-off-by: Horia Geantă <horia.geanta@nxp.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>