brcmfmac: fix problem connecting to AP without security

The bcm43236 device showed having an issue connection to an AP without
security when auth_type was set to automatic. For this particular device
a workaround is made by selecting open-system. This problem does not
occur when using wpa_supplicant as it will not use auth type automatic.

Reviewed-by: Hante Meuleman <meuleman@broadcom.com>
Reviewed-by: Pieter-Paul Giesberts <pieterpg@broadcom.com>
Reviewed-by: Piotr Haber <phaber@broadcom.com>
Signed-off-by: Arend van Spriel <arend@broadcom.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>