Use minimal scan delay upon EVENT_INTERFACE_ADDED

Use minimal scan delay upon EVENT_INTERFACE_ADDED

This patch resets the static interface_count to zero in case of
wpa_supplicant_driver_init() call for wpa_s which is in
INTERFACE_DISABLED state. This interface_count is used for the delay of
the scan which is now minimal for dynamically added interfaces. This may
collide with a scan for another interface, but the same is true for any
chosen delay in this scenario. Also the state change to DISCONNECTED is
moved to wpa_supplicant_driver_init() so it will move from
INTERFACE_DISABLED to INACTIVE when there are no enabled networks.

Tested-by: Hante Meuleman <meuleman@broadcom.com>
Signed-off-by: Arend van Spriel <arend@broadcom.com>