crypto: ecdh - fix ecdh-nist-p192's entry in testmgr

Add a comment that p192 will fail to register in FIPS mode.

Fix ecdh-nist-p192's entry in testmgr by removing the ifdefs
and not setting fips_allowed.

Signed-off-by: Hui Tang <tanghui20@huawei.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>