drivers: staging: wilc1000: use 'void' for no arguments functions

Added 'void' keyword in the paranthesis of function definitions, when
there are no arguments to the functions.  This fixes the checkpatch.pl
error - "Bad function definition 'function()' should probably be
function(void)".

Signed-off-by: Chandra S Gorentla <csgorentla@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>