staging: wilc1000: change data type of result in handle_get_mac_address

This patch changes data type of result variable from s32 to int. result
is used to get return value from wilc_send_config_pkt that has return
type of int.

Signed-off-by: Chaehyun Lim <chaehyun.lim@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>