staging: wilc1000: fix line over 80 character in handle_disconnect()

Refactor handle_disconnect() to avoid line over 80 characters issue
reported by checkpatch.pl script.

Signed-off-by: Ajay Singh <ajay.kathat@microchip.com>
Reviewed-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>