staging: wilc1000: change return type to 'void' for wilc_wlan_set_bssid()

Cleanup patch to use 'void' return type for wilc_wlan_set_bssid(),
as its always returns the same value.

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