wlcore: send EAPOL frames with voice priority

Send EAPOL frames with voice priority by setting (the new)
TX_HW_ATTR_EAPOL_FRAME bit in tx attribute.

Sending EAPOL with voice priority fixes re-key
timeout issues during heavy traffic.

Signed-off-by: Igal Chernobelsky <igalc@ti.com>
Signed-off-by: Eliad Peller <eliad@wizery.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>