SAE: Enable only groups 19, 20, and 21 in station mode

SAE: Enable only groups 19, 20, and 21 in station mode

Remove groups 25 (192-bit Random ECP Group) and 26 (224-bit Random ECP
Group) from the default SAE groups in station mode since those groups
are not as strong as the mandatory group 19 (NIST P-256).

In addition, add a warning about MODP groups 1, 2, 5, 22, 23, and 24
based on "MUST NOT" or "SHOULD NOT" categorization in RFC 8247. All the
MODP groups were already disabled by default and would have needed
explicit configuration to be allowed.

Signed-off-by: Jouni Malinen <jouni@codeaurora.org>