crypto: api - Disallow identical driver names

commit 27016f75 upstream.

Disallow registration of two algorithms with identical driver names.

Cc: <stable@vger.kernel.org>
Reported-by: Ovidiu Panait <ovidiu.panait@windriver.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>