crypto: Add CRYPTO_ALG_KERN_DRIVER_ONLY flag

The added CRYPTO_ALG_KERN_DRIVER_ONLY indicates whether a cipher
is only available via a kernel driver. If the cipher implementation
might be available by using an instruction set or by porting the
kernel code, then it must not be set.

Signed-off-by: Nikos Mavrogiannopoulos <nmav@gnutls.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>