While the EAPOL-Key MIC derivation was already changed from SHA256 to
SHA384 for the Suite B 192-bit AKM, KDF had not been updated similarly.
Fix this by using HMAC-SHA384 instead of HMAC-SHA256 when deriving PTK
from PMK when using the Suite B 192-bit AKM.
Signed-off-by: Jouni Malinen <j@w1.fi>
