staging: wilc1000: refactor wilc_get_mac_address() to avoid deferred handling

Avoid handling of WID_MAC_ADDR wid command in deferred approach. Instead
of posting the wid to workqueue now handle directly from the caller
context.

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