Extend RESEND_* test commands to allow forcing plaintext TX

Extend RESEND_* test commands to allow forcing plaintext TX

This allows hostapd testing functionality to be forced to send out a
plaintext EAPOL-Key frame with the RESEND_* command. That can be useful
in seeing how the station behaves if an unencrypted EAPOL frame is
received when TK is already configured.

This is not really perfect since there is no convenient way of sending
out a single unencrypted frame in the current nl80211 design. The
monitor interface could likely still do this, but that's not really
supposed to be used anymore. For now, clear and restore TK during this
operation. The restore part is not really working correctly, though,
since it ends up clearing the TSC value on the AP side and that shows up
as replay protection issues on the station. Anyway, this is sufficient
to generate sniffer captures to analyze station behavior.

Signed-off-by: Jouni Malinen <jouni@qca.qualcomm.com>