brcmfmac: set wpa_auth to WPA_AUTH_DISABLED in AP/OPEN security mode

When setting wpa_auth to WPA_AUTH_NONE(1) in AP mode with WEP security,
firmware will set privacy bit and add WPA OUI in VENDOR IE in beacon and
probe response. The security type in softAP beacons confuse the
supplicant in client side, and the user client will see [WPA-?] in
supplicant scan result. So we set WPA_AUTH_DISABLED in softAP mode with
OPEN security.

Signed-off-by: Wright Feng <wright.feng@cypress.com>
Acked-by: Arend van Spriel <arend.vanspriel@broadcom.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>