staging: wilc1000: remove unused 'lock' varible in 'wilc_priv' structure

Cleanup patch to remove the unused variable from 'wilc_priv' structure.

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