Make it possible to specify the SAE mechanism for PWE derivation. The
following values are possible:
0 = hunting-and-pecking loop only
1 = hash-to-element only
2 = both hunting-and-pecking loop and hash-to-element enabled
hostapd currently defaults to hunting-and-pecking loop only.
Signed-off-by: Michael Yartys <michael.yartys@protonmail.com>