crypto: api - Clear CRYPTO_ALG_DEAD bit before registering an alg

Make sure CRYPTO_ALG_DEAD bit is cleared before proceeding with
the algorithm registration. This fixes qat-dh registration when
driver is restarted

Cc: <stable@vger.kernel.org>
Signed-off-by: Salvatore Benedetto <salvatore.benedetto@intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>