crypto: ecdsa - Register NIST P384 and extend test suite

Register NIST P384 as an akcipher and extend the testmgr with
NIST P384-specific test vectors.

Summary of changes:

* crypto/ecdsa.c
  - add ecdsa_nist_p384_init_tfm
  - register and unregister P384 tfm

* crypto/testmgr.c
  - add test vector for P384 on vector of tests

* crypto/testmgr.h
  - add test vector params for P384(sha1, sha224, sha256, sha384
    and sha512)

Signed-off-by: Saulo Alessandre <saulo.alessandre@tse.jus.br>
Tested-by: Stefan Berger <stefanb@linux.ibm.com>
Acked-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>