Bluetooth: Switch SMP to crypto_cipher_encrypt_one()

SMP does ECB crypto on stack buffers.  This is complicated and
fragile, and it will not work if the stack is virtually allocated.

Switch to the crypto_cipher interface, which is simpler and safer.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Acked-by: Johan Hedberg <johan.hedberg@intel.com>
Tested-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>