net: l2: wifi: Fix issue command wifi connect fail.

Increase wifi connect input parameters max count to 13. Previous count
7 is not enough if other security type is supported.
When enabling softAP, the parameter cnx_params in cmd_wifi_ap_enable()
is with static key word. Then the parameter will always save
configurations of last time. Remove static keyword to eliminate effects
of configs from last tim and do memset before setting up softAP.

Signed-off-by: Hui Bai <hui.bai@nxp.com>