cryptodev: redefine elliptic curve group enum

cryptodev: redefine elliptic curve group enum

- EC enum was renamed to rte_crypto_curve_id.
Elliptic curve enum name was incorrectly associated
with a group (it comes from the current tls registry name).
- Clarified comments about TLS deprecation.
Some curves included are deprecated with TLS 1.3.
Comments to address it were added.
- Clarified FFDH groups usage.
Elliptic curves IDs in TLS are placed in the same registry
as FFDH. Cryptodev does not assign specific groups, and
if specific groups would be assigned by DPDK, it cannot be
TLS SupportedGroups registry, as it would conflict with
other protocols like IPSec.
- Added IANA reference.
Only few selected curves are included in previously
referenced rfc8422. IANA reference is added instead.
- Removed UNKNOWN ec group.
There is no default value, and there is no UNKNOWN
elliptic curve.

Signed-off-by: Arek Kusztal <arkadiuszx.kusztal@intel.com>
Acked-by: Fan Zhang <roy.fan.zhang@intel.com>
Acked-by: Akhil Goyal <gakhil@marvell.com>